Flyin’ High: JDSLabs C421

The Final Production Version

Early in January I posted an impression of the C421 on Headfonia’s Facebook ( since I was enjoying the amp very much and wanted to spread out the word. I wanted to do a review then, but since the enclosure was to receive some further treatment, I thought I had better wait until the final enclosure is finalized.

Eventually the enclosure is finished and I received the final C421 from John. The black aluminum enclosure has now received a brushed hairline finish, and a matte black finish instead of glossy on the prototypes. It’s nicer looking, but still not a big improvement as a whole. Looking at the amplifier as a whole, I think the enclosure design is the one area that still needs an improvement. It’s not terribly bad, actually, as the whole thing is still cased in aluminum, precise cuts on the front and back plate, and high quality jacks and switches. But a nicer case is definitely welcome. Lieven told me he likes the look of the C421, but we all know I have a better sense of aesthetics than he.

Aside from the case, the other significant changes to the final version is the lower gain levels (2.5x versus 3.5x gain), different brand gain resistors, different brand 3.5mm jacks and toggle switches.

Comparison to the Ibasso D-Zero
The C421 is a clear step up from the D-Zero in terms of sound quality. The D-Zero may be the better value amp as it comes with a USB DAC for $109. However, if judging solely from the sound quality, I would go for the C421 clearly for the superior midrange, an overall better treble/midrange/bass balance, and most of all the superior soundstage.

Comparison to the Headstage Arrow 3G and 4G
The Headstage is a nice amp and is still the slimmest one of the bunch. Build quality wise, it is still better than the C421 (in fact I think the D-Zero also has a better build quality than the C421). However I always find its soundstage to be quite flat. The 3G variant has a dark tonality and was quite full sounding in the mids and lows. The 4G version changed things a little by adding more treble to the mix, and you get a slightly more airier sound. Still it didn’t improve on the overall soundstage performance (airy sound is not the same as true three dimensional soundstage), and the treble area was dryer in comparison to the 3G.

In many areas I find the C421 to be better sounding than both the 3G and the 4G Headstage amps. The soundstage performance was clearly better, as it possess both width and depth not heard on the Headstage. Midrange was also sweeter and clearer, the treble more airy while still very smooth. The only advantage the Headstage has over the C421 is in the bass section, where the Headstage has a more proper bass punch.

Comparison to the TTVJ Slim
One of the highlights of the TTVJ Slim is the midrange, but I think the C421 has exceeded it in midrange quality. I also enjoy the mildly darker and more laid-back presentation of the C421 better than the TTVJ. However, the TTVJ still wins when it comes to overall dynamics, micro detail, and bass impact. The TTVJ sounds like a bigger amp than the C421 is.

Comparison to the ALO Rx
Like the TTVJ Slim, the ALO Rx also sounds bigger than the C421 is. Better dynamics and bass impact than what I get from the C421. However, the ALO Rx is known more for its spacious sound and powerful bass impact, but not so much for a full sounding mids. Again in this case I think the midrange of the C421 keeps on winning me over. Also, while the ALO Rx ultimately has a wider soundstage, the C421 has a better depth and ambiance over the Rx.

Comparison to the Objective 2 Amp
This is the only non-slim amp comparison in the list, but I know that a lot of people have been asking for this comparison. The O2 is a better amp technically, with a blacker background, wider soundstage and clearer instrument separation. The C421 wins on midrange quality and portability factor.

End Words

I enjoy being able to recommend good sounding gear to people, even more if it happens to be affordable to the majority of my readers. Prior to the C421, the JDSLabs Cmoy is perhaps the one amp that I made the biggest number of recommendations for. One reason is definitely the $60 price tag, but even more is the fact that the Cmoy actually sounds very good. However, it was still limited in terms of features.

It would be nice to have something that sounds like a Cmoy in a slimmer package, and not only with a recharging circuit but USB-based charging. Many great amps like the RSA-71A fall short when it comes to day-to-day usability because they don’t come with recharging circuits, so USB charging ranks very high on my list (most of us have too many gadgets, each requiring its own dedicated charger).

As I mentioned earlier, I told John that I would’ve been very content even if the sound is only on-par with the Cmoy. (In case you’re wondering, the C421 makes the Cmoy sound congested so it is clearly better). It’s true that initially I just saw the C421 as another amp maker’s effort to expand their product line. Now that I’ve lived with it for 3 months, I’m definitely going to make a lot of recommendations for this amp.


On the picture gallery: I apologize for the lack of comparative pictures to the other amps.

jdslabs_c421_05 jdslabs_c421_04 jdslabs_c421_03 jdslabs_c421_02



Flyin’ High: JDSLabs C421
4.67 (93.33%) 3 votes

  • Hi Mike,
    Do you think the C421 is sufficient to drive the HD650 properly?

    • L.

       I use the C421 daily at the office with my HD650. And while it does a sufficiently & good job, the HD650 on a full sized setup does sound remarkably better, but that’s only normal.

      • I see, so it should be enough for it to sound like a proper HD650. Thanks!

      • Damián Bonadonna

        How do you use an open back headphone in the office? Just curious because my office is pretty quiet and I think everybody will listen to my HD598 🙁

        • L.

          I have my own private office, just for me. And my Senns

        • L.

          private office 😉

    • Geoffrey,

  • Damián Bonadonna

    Hi Mike,

    Would you pick this one over MS 2 or DACport LX? I am also like you interested in fuller mids and instrument separation. The LX looks superb but I don’t know if it will alone provide those full mids!

    As you may know is for the HD598 :D.

    Looking for simplicity! And to connect to Laptop mainly (to Android is a nice to have).


    • Trent_D

      MS2 or Dacport LX are DACs. The C421 is a amp. They are two very different things.

      • Damián Bonadonna

        Thanks Trent. It happens that quite often I read Mike recommending them for their fuller mids. So maybe… they will alone provide a really good upgrade.

        My notebook has a Realtek AC269 and with the HD598 I cannot hear any hiss, noise… nothing. I guess they are sounding a little harsh in the treble side so maybe an amp is better than a DAC. And I can use the amp with my SGS too.

        But I’m just thinking still not decided what to get.

        • Just an idea… get the C421 and a cheaper entry level DAC like the Fiio E10. Both would still fall under the price of one Dacport LX.

          Then you can listen to the C421 alone out of the Realtek.
          The E10 alone without the built in headphone amp.
          The E10+C421.

          Then you’ll know if the DAC or the Amp will make more difference in your case.

          Or better yet get an E10 with a Cmoy, just so you’ll have a better idea of what you need: a DAC or an amp.

          All those components I recommend should help you to get fuller mids, smoother treble, and better instrument separation.

          • Damián Bonadonna

            As always, thanks Mike!

  • Jim

    sorry, double post

  • Jim

    Hi Mike,

    What would sound better between:

    1) Laptop -> E17 -> RE-262
    2) iPhone4S -> C421 -> RE-262

    I know that the C421 will beat the E17 coming from the iPhone4S, but I’m curious between the 2 setups above, I’m assuming the E17 DAC > iPhone4S DAC whereas the C421 AMP > E17 AMP so its hard to tell which is better.

    • I think you’ve got that right.. the E17 DAC is very good compared to the iPhone and on the other hand the C421 amp is also very good compared to the E17’s.

      I don’t think it’s going to be as simple as which is going to sound better, as having a good DAC has its own advantages and having a good amp also has its own advantages.

      Perhaps an analogy is like cooking. Fresh ingredients + Bad chef, or Bad ingredients + Good chef, which will give you the best food? 😉

  • PCMM1

    Mike, I would like to ask how is C421 when compared with Just Audio uHA-120?
    I am now thinking of uHA-120 (Upgraded of vol control pot version) and this. ^^

    • L.

      Hi. The C421’s soundstage is slightly better, music feels less compressed, and its the airier of the 2 amps. The µha is the darker one with the better bass. Both are very enjoyable & fun, but I think the C421 has the edge over the µha in total, and it has a gain and bb switch 😉

    • L should be the one you listen two as I’ve never listened to the uHA120, but L has.

      • PCMM1

        Thanks Mike and L.
        I know which one suits me more. ^^

  • John Kim

    Hi Mike. How is the volume on low gain? I was hoping to use this with my ES5, but I’ve heard that the volume is pretty loud for sensitive IEM’s.

    • L.

      It is indeed, its milimeter work…

      • John Kim

        Yeah, I don’t mind training my fingers for that but the thing I’m worried about is channel imbalance at very low volumes.

        • John Kim

          Oh, and my files are all matched to a volume of 80db using mp3gain compared to the ~96db of most original music files so I guess this might help?

          • John I will check on that and get back to you.

          • John,
            I tested this with my JH5 Pro. I don’t have a problem with the loudness levels, it’s just that at extremely low level listening levels, there is some channel imbalance (like with all analog pots)

            • John Kim

              Ah great. Thanks for testing that out for me. I do listen at low levels, but I don’t think there would be a problem with that. Now to decide on 8620 vs 2227!

              • You’re welcome John.

                PS: You know my thoughts on the 8620 vs 2227. 🙂

                • John Kim

                  I do indeed. Your review makes it clear who the winner is, but some head-fiers think otherwise. Tough decision!

                  • You should go with OPA2227. 😉

  • What DAC would go well with this?

    • Stephen,
      You can look into the recommended DACs section, they should all pair well with the C421.

  • Which version of the C421 do you think will sound better with the HD25-1 II (AD8620 or OPA2227?)


    • L.

      As you probably read (I hope), we are 2227 fans, on Head-fi, where you asked the same, they will probably say 8620 😉

    • The OPA2227.

  • Chris Wen

    Hi Mike,
    Thanks for the great review!
    I am currently considering buying a C421 for my ER-4B. I somehow worry that the C421 may still not powerful enough to drive the 4B well (I dont mean perfect.). I have a D-Zero and 1/2.5x Objective 2. However, when playing with these two amps, the sound out of 4B is thin and distant. Perhaps I should make things easy and get a Phonak 112. No reason to attempt changing the 4B acoustically to another earphone anyway.
    Have any comments? I am always happy to exchange opinions with gurus like you:)

    • Chris,
      The ER4 doesn’t need a lot of current, just voltage. I’m quite confident that the C421 has enough voltage gain for the ER4B.

      Generally the D-Zero and the O2 are thinner in mids than the C421, so this may be the pairing that you’re looking for. Go for the OPA2227.

      • Chris Wen

        Hi Mike,

        Thanks for the recommendation! I think you are right about 2227. I read some other comments on these 2 versions. It seems 2227’s warm sound is going to work better with ER4B that has an analytical sound.

        • Yes. I like the OPA2227 C421 with the ER4P/S.

  • Mike, Which version of the C421 do you think will sound better with the JH16 (AD8620 or OPA2227?)

    • I haven’t tried this with the JH16, sorry.

  • Thanks for another wonderful review. Since you have used both the National and C421 which one would you recommend for sensitive IEMs(XBA-4) and analytical one (ER-4S). It seems like national from what I have read has more warmth wherease the JDS lab amp has more detail.

    • Yes I think you are right. I would go with either one. Personally I like the National better as it is darker and has fuller lows, which IMO fits both the XBA4 and ER4.

    • The ER4S: National would give you more bass weight (that’s what I’d go for), C421 would give you more warmer mids. Both are good choices.

      XBA-4, I don’t really have too much experience with it but the Portaphile 627 totally transformed it.

  • how does it compare to Little Dot mark 1 ?

  • how is it compared with the Audinst MX1 ?

  • is it worth to upgrade cmoy jds labs to c421 with this price tag???

    • I think so, but everybody’s wallet is different.

      Not only do you get better sound but also better features and a more portable enclosure.

      • do you have c421 unit for demo on your store which open next saturday?

        • Yes we should have that.

  • Damián Bonadonna

    Now I’m understand why the pics are overexposed 😛

  • Both amps are nice, though I like the JDSLabs better.

  • alf

    which is better for HD650, C421 or RSA hornet

    • I would go for the RSA Hornet.

  • Damián Bonadonna

    Hi Mike,

    As you may know, I bought C421 and Dacport LX based on your recommendation :).

    Where I’m living now, the HD800 is around 1400 USD which I guess is a good price. The HD650 is around 500 (not so good price).

    My “high-end” headphone now is the HD598 but I find it a little fatiguing and thin sound. The most expensive HP I have is the B&W P5, but is mostly for the office, I think the HD598 is a better performer overall.

    So, I’m looking for a relaxed sounding pair to mostly listen to acoustic/voice-centric songs and rock/pop like Oasis, Lifehouse, Norah Jones and Adele. But I really listen to a wide music range, except electronic/rap stuff. By relaxing I mean not fatiguing, but I want the musicality to be there.. mostly mid range and bass (not bloating).

    My question is, would it be a crime to buy an HD800 and use it with my combo? I don’t really want an uber expensive headphone amp cause I usually travel a lot, moving the amp is kind of a limitation. The sell Asgard and Lyr around here. But again, I really want to avoid big boxes.

    As always, thanks for your inputs.

    • L.

      Senn HD650 gets my vote

      • Damián Bonadonna

        Hi L, thanks.

        For what I read the HD650 is also very scalable. Now.. knowing that is a 10 years old headphone, how it does compare with recent offerings like HE400/HE500?

        I might want now only one headphone for home use and so many options are driving me crazy :P. The problem with not so mainstream headphones is that they are difficult to find here. I bought the P5 because the only similar option was the HD25 Adidas, and was expensive too. Also, for office use the P5 look better and really I don’t like the plastic construction of the HD25.

        For the HD650, I know it is praised everywhere so it is kind of a safe bet. I can also try it soon. What I also think is that the looks are not of my taste and that they get scratched easily.

        What other options do I have as a real step from the HD598?

        • Take a read on Mike’s review on the HE-500. HE-500 works far better with pop music as opposed to the HD650 for slower paced jazz and classical, but driveability wise, I’d still say the HE-500 is harder as a good solid state is really needed for the job. You could pair lower end amps and always feel that it’s never enough. With the scalability of the HD650 however, low end gear works great as well. Going higher end however, rather unlocks the HD650’s potential as a resolving and technical headphone.

          The HE-400 is a very good step up in my opinion and you don’t need something ridiculously powerful to drive it so it’s technically more easier on your wallet than the HD650. I have not ABed these two however so you’re going to have to ask Mike to take a trip down memory lane.

          • L.

            I wouldn’t advise the HE-500, you would need a good amp (I prefer it on tubes, not ss) and it isn’t the best for your genres. I would say the HD650 is best for pop, not the 500 (which is best for jazz, etc). The only other option, if you want an open headphone is the HE-400, which doesn’t need amping, and it is a great alrounder. You can also check out the HD25, good price and good sound, but on ear and plastic ( but very durable).

            I love the look of the HD650 🙂

            • took a listen today, perhaps jazz does work better on the HE-500 but it really still is hard to drive as heck, but honestly I don’t see how the 650 plays pop well :

              • L.

                I think it does. HE-400 does it better but still good on the 650. What kind of pop do you have there :p Let’s let Mike decide 😉

                • Damián Bonadonna

                  Actually, what I call pop is Adele or Lifehouse. I listen a lot to Chris Cornell/Eddie Vedder/Coldplay style, mostly now acoustic and vocal stuff. I really don’t like actual UK TOP40 for example, too much electronic in there..

                  Problem is that I don’t own a high end headphone, so I would need a all arounder. I really like the W3000ANV that is closed, so is a change from the HD598. Now.. for 1200 USD, does it justify it? I don’t know… It is closed, which means that I might use it as an office headphone too.

                  I really like to read this much about headphones, but taking the plunge and decide for one is really difficult for me :P.

                  I’m starting to like the non-fatiguing and laid back nature of the P5. I can listen to Adele without piercing my ear drums. I read that HE-500 can be a little fatiguing and I don’t want that. The OP2227 add a touch of warmth but I don’t use it always.

                  I want to thank you Lieven and Mike for discussing this here. Is really constructive for me :).

    • No, it would be a waste to buy the HD800 and get the most out of it. Look harder for good deals on the HD650, something like this.

      Asgard and Lyr have a smaller footprint that you think to be honest. They’re incredibly small. Where are you based?

      • Damián Bonadonna

        Hi Nick,

        I’m based in middle east now, I should be more time in Dubai but I travel a lot for work so I don’t have my own place yet.

        I guess I will have to keep the HD800 for when I stay in one place and put some nice amp for it.

        Middle east in not a good place for audiophiles (I’m not but I try). Not many options here.. and if there are the prices are not that good. HD650 is 517 USD in Dubai.

        I guess I messed up buying the HD598, because if I buy the HD650 I guess the former will not get used that much. As they are open I can only use them at home, and for office I bought yesterday a P5 (expensive as hell in Kuwait, but it was my birthday present :P).

        • Like I said, you can get the HD650 for a good price on the online site I’ve showed you, free shipping worldwide too. I’m not discouraging you to get a HD800 but the nice amps that work best for the HD800 tend to be huge tube amplifiers.

          The HD800 at 1400USD is good price, yes but I’m also telling you that you should try both cans first. The HD650 is far more easier to appreciate than the HD800 running out of something like the Schiit Amps. One of the many problems I see that with flagships like the HD800 is that people buy and sell them out almost immediately because it doesn’t work for them. Synergy wise, the HD800 won’t fare well with pop music either.

          From P5 and 598 to the 650 and 800 is a massive leap, seriously.

          • Damián Bonadonna

            I’ve just checked they have free shipping, thanks!! 🙂

            They also have the wooden ATH, they are not that recommendable as the HD650? (W1000X, W5000 and W3000ANV). I know they are quite expensive and closed, but they beuty always caught my attention.

            • Mike has highly praised the W3000ANV, check out his review.

              • Damián Bonadonna

                Nick, I think I’ve read every review here in HF haha. With so many praised headphones is very difficult to choose one. I also check hed-fi, innerfidelity and Almost everyone agrees on the HD650 being great and scalable. I also read in CNET that they were happy with the HD800 out of an iPod.. so it is kind of polarizing. If I buy the HD800 and it works as the HD650 but then I gain 1000X scalability I might invest for years to come. Hahaha this is crazy.. so many options!!

                Whatever I but I really want to justify the investment as we are not talking about 100 USD.

                • Damian,
                  There is no way you can be happy with an HD800 out of an Ipod.

                  I think you should try the HD650. I don’t want to push it too much, but it’s far more popular than the HD800 and for reasons other than simply the price. If one day you decide to spend $3,000 on a big tube amp, the HD650 scales up very well so you’ll be able to appreciate the improvements as well.

                  • L.

                    yes, I would never get the HD800 for your musical preferences

                • Thing is, headphones that jump at you with it’s sound is so easy to appreciate at first listen out of a simple setup, but it’s the Sennheiser bunch that grows on you which Mike and L. would agree on as you scale up your source and amplification components

                • I don’t object most reviews as long as they don’t have objectivity in mind… because the biggest slap in the face to those reviewers is that if all headphones are “ideally” tuned to a flat frequency response, there’s no point making headphones.

                  CNET isn’t objective but look at headphones from “pros” and “cons” perspective such as listing “stiff cable” and “high $$$” as cons also don’t pay much attention to listening to headphones but at least don’t dismiss the Sennheisers as crap headphones, but honestly doesn’t give much impressions on sound. I would say they are more orientated towards the general consumer crowd.

                  CNET probably doesn’t have that sort of appreciation towards audio gear as readers on headfonia have, and they don’t really have much comparisons to reference their opinions on headphones.

                  What I honestly love about headfonia is that it is purely subjective which is what musical listening is supposed to be, and that is understanding that different headphones work for different people and music. Just like how people think Monster Beats are awesome headphones. (As a fashion accessory, I give it to them). Subjective tests such as soundstage imaging, resolution and clarity simply can’t be “measured” physically, and everyone’s opinions here counts.

                  Honestly, go with the HD650. You won’t regret it. I think I’ve dedicated myself to become an exclusive Sennheiser listener and an exclusive Bottlehead Crack user. I may consider getting a pair of HD700 as well but for now, upgrading my Crack and rolling in tubes actually made me slap myself in the face as I’ve realized that the HD650 is far more resolving than what I thought it was capable of. It isn’t the most resolving and technical headphone out there, but the HD650 was always symbolic of the Sennheiser sound which I’ve grown to appreciate and enjoy so damn much.

          • do you know cheaper online store that have price like you post here?

            • No not really. Those prices I’ve posted are pretty much exclusive to local retail sales in Hong Kong only.

  • how is it when compared to the pico slim ?

    • Sorry what compared to the Pico Slim?

  • Hi Max! Yes the C421 is a good amp!

  • Trent_D

    Mike and L, I have a chance to try the c421. I know that Cmoys do a very good job with high impedance headphones. Would the c421 even be an improvement with the hd650?

  • Hi Mike,

    Great review!

    I’m trying to decide on an amp for my DT770/250 & HD25-1

    Both are good in bass and highs are a bit harsh, so I’m looking for a somewhat darker amp that doesn’t accentuate the bass (but do have bass boost for when I’m riding the bus).

    What do you think would be more suitable for this? (300$ range)

    From what I’ve read it’s between the C421 and the Array Headstage 4G



    • Hi Eli,
      The Headstage 4G is a bit harsh on the treble. 3G actually is better for what you’re looking.

      Another option if you are open to suggestions is the Matrix Mini Portable

      • Thanks Mike!

        Do you consider the C421 (2227) to be dark or bright sounding?
        Can you recommend on other options as well? the Matrix Mini is on the heavy expensive side of things.

        • L.

          It’s dark. didn’t the review give that away? 😉

        • Trent_D

          Can’t you use the e17 to lower the treble a bit via it’s digital controls?

          • I can and I am, but with the e17 I have to remember to lock it so the buttons wont pressed by mistake (and I keep forgetting and find it on the go without charge too many times). Also, I want a better amp the sound stage of the e17 is pretty small and the sound is not as smooth as I want it to be

        • Eli,
          The Apex Glacier is not a dark amp. The C421 is darker but the darkest is Matrix Mini. If the Matrix is too much for your budget you can look at the ALO national as well

          • Thanks for the quick replies.
            I’ve read your review on the National, sounds pretty good.
            But I’m worried it will have too much of bass impact on my already bass heavy DT770/250. am I right to worry about that ?
            Could it be a problem?

            • Mike?

              • You’re asking about the National + DT770/250?

                The National has a tight full bass that’s not like the usual amplifiers (say Cmoy) with bass boost on. The sound is very nice, it’s not the boomy loose excessive bass.

                I would even use it with the DT770 80Ω which has more bass than the 250Ω.

                • Thanks!

                  If it’s ok I want to ask the same regarding the Matrix Mini.

                  In the review for it you mention that there is a lot of bass in it.
                  So, as I think that the bass in my DT770 is more than enough and sometimes too boomy as is, would the Matrix Mini make it more boomy/bassy?

                  Thanks again,

                  • Nope it would be good. The Matrix Mini’s bass is tight and well controlled. Not boom boom type.

  • I bet you’ve made your decision in the months since then, but I thought it might be nice to let others know my experience with the AKG K550 and the c421.

    I’m using the following: iPod classic -> CLAS v1 -> c421 -> AKG K550. I am not a bass head but for a lot of rock, pop and electronica I find I need to use the bass boost switch on the c421 to be happy with the bass impact. Ad frankly then it might feel a little too punchy for my liking at times.

    That’s my main criticism of the K550 headphones – they are just a little low on bass impact. My other headphones are the Sennheiser HD558 and those don’t need the bass boost switch.

    I’m mulling switching to the limited edition DT770 so I don’t need the bass boost switch of the c421 but retain an otherwise similar sound to the K550. At least, that’s the plan!

    • Thanks, John.

      I share the same concern about the K550: bass impact.

      • Thanks Mike. I just had a thought. If I want to get that more impactful bass (but not as heavy as c421 bass boost switch), which option do you think would be better:

        1. Replace the c421 with the National, or
        2. Replace the K550 with the DT770 Limited Edition?

        • Replacing the headphone is going to be the better choice. Gets you there faster.

          Have you listend to the HD650? That Senn is king when it comes to bass impact.

          • Trent_D

            I am listening to the HD650 right now with the C421 (out of the dacport lx) and it sounds very nice. I was surprised what a big step the C421 was over the cmoy. Now I just can’t wait to hear how much further the crack takes it.

            • Trent_D

              and, PS, I just recently bought the HD650 to replace my K550.

            • L.

              thx for reminding me 😉

            • That’s nice Trent.

          • Thanks Mike. I haven’t listened to he 650 but I’ve been avoiding it because I need closed phones for my normal use :(.

            • Trent_D

              L did say the C421 was a nice pairing with the DT770 LE. They sound like a really good deal.

              • L.

                A warmer tonality and good bass. + You have the option ti turn off the bass boost on the C421

            • In that case just go with the DT770 😉

  • Hi, I just got my self a c421, but, in my ears the sound is almost identical to the E17, are they that close in sound or I’m missing something?
    Would the Matrix Mini be a noticable upgrade?


    • L.

      Should be different. what are you listening with?

      • iPod > LOD > C421 > DT770/250

      • Does it need a lot of burn in time? I gave it about 20 hours

  • Regis

    Hello there, I’m looking at the c421 for my AKG k550’s but I’m not sure which version to get…your review makes me think the OPA2227 version would be best but I want confirmation. Also is the impedance on the amp low enough for the k550s?

    • L.

      The new version with the ferrite change and the 2227 should be just fine!

      • Regis

        so the 2227 would complement the akg k550 more than the AD8620? would make sense since the ad8620 is the more clinical sounding of the two versions and the k550 definitely needs more mid presence and bass, right?

        • The AD8620 is not clinical. It’s more forward and the bass is punchier, but the soundstage is smaller and the mids are more congested.

          I really don’t think going either with the 2227 or the 8620 would make enough of a difference to the K550.

          Going with a different headphone is a better option.

          • Regis

            What amp or dac would be best for k550s? I just want one with low impedance and bass boost. I like the k550s and find them really unique so ill keep them. Love them for classical, acoustic performances, jazz and the like but of course, they dont work at all for me for pop, rock, metal and edm but what would you suggest as the best semi-open or closed headphone for more synthetic genres or fast pass bass rhythms? Price doesn’t matter. I was saving up for ed8’s but interested in your opinion. I want comfort and bass impact, specifically in sub bass.

          • Regis

            What amp or dac would be best for k550s? I just want one with low impedance and bass boost. I like the k550s and find them really unique so ill keep them. Love them for classical, acoustic performances, jazz and the like but of course, they dont work at all for me for pop, rock, metal and edm but what would you suggest as the best semi-open or closed headphone for more synthetic genres or fast pass bass rhythms? Price doesn’t matter. I was saving up for ed8’s but interested in your opinion. I want comfort and bass impact, specifically in sub bass.

          • Regis


  • lcamtai

    What will happen if I connect Audeze LCD-2 re 2 with C421. My friend has a LCD 2 and I would like to borrow him just for a test for few days. Reading on the internet that LCD2s are amp picky and the manufactures said that LCD2s need at least 1mW to shine. Just curious if Mike has ever tried to pair high impedance output headphones or hard to drive ortho headphones with C421 yet?

    Thanks so much.

    • Do you already have the C421? It isn’t sold anymore new. It was replaced by the C5.

      • lcamtai

        Yes, I have C421 OPA2227 which I think is the most powerful OPA among 3 OPAs. I bought it in August last year.

        • I don’t think I’ve tried that but I can give it a try

          • lcamtai

            Thanks and wait for your results.

            • L.

              I’ll try it later as well. just for you! 😉

              • lcamtai

                Thanks and try C421 with Fostex Mad Dog as well. However I have already thought that C421 does not have enough power to drive LCD but Mad Dog is another story. Look for a new review Mad Dog with Alpha Pad. Is Alpha Pad idea of Mike?

                • L.

                  Don’t have that one, sorry

                • I tried the C421 with the LCD-2. Sound was good, loudness level was good. I just didn’t hear the bass impact that the LCD-2 is famous for.

            • L.

              Sound is ok but there’s a big but. With the bass boost off, the sound is really lacking in bass, but with the BB on, there isn’t enough power to keep the bass in control. Bass heavy music was a no go. Imo

  • Ike

    Hello Mike! What about this C421 (AD8620) compared with Sony PHA-1? Would the sound change so much from C421 to PHA-1? And how about if i use with UE900 and HE-300 for PHA-1? Is it worth to change from C421 to PHA-1 with iPOD Classic i have?

    • You will gain a superior DAC section if you’re just using an iPod Classic. The problem is that I’ve listened to two PHA-1s so far and the sound quality is very different. One PHA-1 I won’t even bother get to replace the basic iPod. On the good PHA-1, however, it’s definitely a step up from an Ipod+C421. Funny thing is that the PHA-2 I listened to was also not as good as the “good” PHA-1. Figure that out.