Bakoon International Products HPA-01M: For Ears And Years

Going Deeper

The HPA-01M, like I said, is an analog amp. That means it’ll be extra picky about the source used. For this review I mostly used it with the AK240 and with the Resonessence Labs HERUS and my laptop during office hours. The M will immediately show you how good/bad your source is, it’s very transparent.

When you’re using the HPA-01M, you will notice it gets warmer as hours pass. Especially when using the voltage output with high impedance dynamic headphones like the T90 Tesla and the Sennheiser HD650 the M heats up quite a bit. You won’t burn yourself or anything but it does make for a nice hand warmer.

The M plays loud. It of course doesn’t have as much power as the full sized units but it’s powerful enough for all orthodynamic headphones. Again, like with the HPA-21, the planar technology headphones really shine with the SATRI Current output. I haven’t felt the need to use the gain switch for the Current output with any of my orthos on the 01M. With my custom IEMs and some off the full sized headphones, I have to turn the volume of my source down to be able to listen to it. Even with 0 volume on the dial, you can hear music playing with sensitive monitors like the Earwerkz Legend R when your source has a powerful Line Out. The range of the volume pot isn’t the biggest: it gets loud quickly but then stays there. There is some channel imbalance at the very beginning which could be annoying for those who listen at lower volumes. A solution is to lower your sources output so that you have more range on the M’s volume dial. The volume pot also crackles in the beginning with tiny twists and at very low listening volumes:

Marcus, from Headfonics, experienced the same thing and Bakoon explained why that’s happening:

“I’d like to share my feedbacks first regarding about the noise/scratch, it is actually a small amount of DC leakage noise at the initial start-up. Since the HPA-01M is a zero negative feedback amplifier (quite possibly only portable one in the world), there will be a minimal/small amount of DC leakage for the first few gain controls, but it will be completely gone afterwards as the circuit is then more “stabilized” without any DC output. This is also stated in the manual and you will notice that there will be no noise after you control the knob a few times.”

It’s true. It is in the manual and the soft crackling does disappear after a while.

Tantalizing

The HPA-01M does have its specific sound, and I wouldn’t really call it neutral. It certainly adds its own magic to the music. Especially bass and mids have/get great body. The amplifier, with all the headphones and CIEMs I tried it with, is dead silent at all times (except for the light crackle I mentioned). There’s no trace of floor noise and the M has a gorgeous black background. Everything sounds tight, fast, clear and detailed.

Current Output

The most special about all the Bakoon amplifiers is of course how excellent they sound with the orthodynamic headphones when using the Current output. It’s no different here with the Miniature portable amp: the Audeze and Hifiman’s of this world rock like they have never before.

The magic is always there and the planars sound clean, fast, tight, transparent, open and detailed with the right amount of body in mids and bass to make it an unforgettable listening experience. Treble might not be the most extended or detailed but it also depends on the headphone in use. With the HE-560 in example you will have really nice treble as it is one of the characteristics of this specific headphone. I do think the desktop sized HPA-21 sounded even better though.

Most of the other headphones I tried (more on that later) sounded better on the Voltage output but the orthodynamics like the Audeze LCD2, the XC and the Hifiman HE-560 sound almost as good as they can on the current out of this portable device. When you connect a dynamic headphone to the Current out, you will end up with a more forward and aggressive sound with added bass and treble. The Current output isn’t for all head- and earphones and the sound you will end up with will strongly depend on the headphone used. It’s more of a hit and miss, and then there’s your personal preference of course. However with an orthodynamic headphone, this results in a nice sound stage and a fast, detailed and open sound with great clarity. It’s amazing.

It’s clear that the Current output plays at a higher volume. You will quickly notice that when switching outputs. The gain switch only works on the Current out but I never felt the need to use it.

Voltage Output

When using the Voltage output and dynamic headphones, you get a completely different sound. A slightly warmer and smoother/laid back sound with an even bigger sound stage and a lot more air. A very relaxed presentation actually. Most people, especially when using dynamic headphones, will recognize the sound they are used to from other amplifiers, in the Voltage output.

There is lots of detail and there especially is more depth in the sound stage with more timbre compared to the Current output (except when using orthodynamics on the current out). The Voltage out delivers a very dynamic and musical sound with great bass and good body in bass and mids. Mid & bass body (and slam) however is way less than on the Current output.Treble isn’t sharp or hot but has a rather relaxed presentation. I do think treble is best on the Voltage out.

On a first listen you would say the Voltage output has more detail. Maybe it does but I do think there’s just as much detail on the Current out. In my opinion you get this idea because the relaxed and open presentation of the Voltage out makes it easier to pick up this detail compared to the more forward and more aggressive sounding Current out. I’m not saying the Current output is aggressive but compared to the voltage output it is more aggressive. And you won’t notice any of the aggressiveness when using orthos. Current or Voltage output, the HPA-01M will always have a top resolution, great clarity and lots of detail.

Sources

I used different sources with the Bakoon M. My favorite one being the AK240: the clarity and detail retrieval of the 240 are superb, that in combination with the bass and gorgeous mids of the 01M make this the best sounding portable combination I own. The DX90 already has slight focus on bass and adds a bit of body to the mids. While this combo certainly wasn’t bad it did sound a bit too much from time to time. I was happily surprised with the new Fiio X3 Second Gen. The new X3 has a great line out it delivered quite a good neutral sound but not AK level. All about the new X3 in next week’s review!

With my laptop, I did end up using the new X3 as a DAC from time to time, but my favorite source was the Resonessence Labs Herus. This little unit keeps surprising me. The sound it delivers is unbelievably good for its price: enormous clarity and detail, and just like with the AK240 this matches perfectly with the 01M. You get a top quality desktop sound from (trans)portable gear.

Headphones, Amps and Conclusion can be found after the click

5/5 - (20 votes)
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Lieven is living in Europe and he's the leader of the gang. He's running Headfonia as a side project next to his full time day job in Digital Marketing & Consultancy. He's a big fan of tube amps and custom inear monitors and has published hundreds of product reviews over the years.

19 Comments

  • Reply March 17, 2015

    cs098

    Interesting, do you think it can power the hd-6? Sounds like a great amp for bright headphones. Or people who adores the dark sound.

    • Reply March 17, 2015

      Headfonia_L.

      The only HD-6 I know is the Sennheiser DJ headphone and that shouldn’t be any problem 😉

      Darker isn’t the right work, unless you find the LCD2 dark. I wouldn’t call it an amp for brighter headphones just cause it works great for the T90. The T90 will always sound like the T90, no matter the amp

      • Reply March 17, 2015

        cs098

        lol he-6 XD

        Yeah I find the lcd 2 to be dark

        • Reply March 19, 2015

          Headfonia_L.

          I’d recommend the HPA-01 or HPA-21 for the Hifiman

    • Reply March 19, 2015

      ohm image

      I’m really beginning to enjoy darker sound.

  • Reply March 20, 2015

    Shini44

    will you update the Hugo (as a dac) + this amp, in this review? or create a whole new one for the epic pair? i do own a hugo, yet not a fan of the amp section of the hugo.

  • Reply July 28, 2016

    John

    What amp should I get for Beyerdynamic T90? I am considering Bakoon HPA-01M, G109S, Beyerdynamic A20, RSA Raptor, and La Figaro 339? I really care for a wide and deep sound stage, and good imaging.

    • Reply July 28, 2016

      Lieven

      You list a lot of good amps there. First choice: do you want tubes or not?
      That would make it Crack or 339. No tubes, I prefer a warmer ss like the V200. the HPA-01M is good but it doesn’t easily have a good synergy with lots of other headphones, so I wouldn’t go there.

      • Reply July 28, 2016

        JOHN

        Thanks for your quick response. Based on your review on the HPA-01M, I thought it was the best SS amp for T90. I believe you said that you even preferred it to V281. Now I am a little confused lol. I think 339 with stock tubes are not that good and I do not know if I can find proper tubes for it (any suggestion?). Crack seems to be a safe bet but I do not know how resolving it is. The thing is I want to keep the cost of amp+DAC under 1200$ and I do not know which one is the determining factor for sound stage and imaging. What DAC would you suggest with 339 or Crack? It seems that Asus Essence One Muses edition has great sound stage and tempting performance/price. Could you make some DAC+amp suggestions for T90? What about the RSA Raptor? Have you ever heard it? 6moons’ says that it has unbelievable sound stage with Sennheiser HD 650. I guess it would become even better with a headphone like the T90. Am I right?

        Cheers

        • Reply July 29, 2016

          Lieven

          It is a really good amp for the T90 but if you’re planning on getting more headphones, the HPA-01M might not be the most versatile amp.

          Have you considered the V200? If you’re not into tubes I suggest to stay away from them, unless it’s something you will want to explore of course.

          There is a lot of good gear in that price range, but I haven’t had the Raptor with me, sorry. I doesn’t mean the T90 would be also great on it, but it could be. The Asus isn’t something I would recommend. How about a second hand Hugo?

          • Reply July 29, 2016

            JOHN

            The only headphone amp that I have is the the one built in the Asus Xonar ST sound card. It is OK with my Grado SR80 and the music genre (Rock by the way) that I am listening to but, for everything else, this combo utterly sucks. Although it is very clear and transparent, there is no sense of sound stage. Everything is played right at your ear drum. This works great for fast paced music like Rock but for movies and everything else is very disappointing. This is the reason why I want to upgrade my audio system a little bit. I read many reviews on different headphones, amps and DACs and realized that the T90 might be the headphone that suits me best. It seems to have great transparency and sound stage but quite picky on amp and DAC. I have never heard tubes but I guess they are superior to SS when it comes to sound stage and imaging which I am looking for. Also, I believe T90 is harsh on trebles which makes tubes better option. The reason I was considering the Asus Essence One as DAC was the fact that many people compared its sound signature to Fostex HP-A8. If this is true, at this price, I think it cannot be beaten. HP-A8 is twice the price, at least in Europe. I think Hugo as amp+DAC was perfect if I could go for something like LCD-2 but since this is not the case, I think using Hugo just as DAC is very expensive. I would really appreciate it if you could suggest some amp+DAC combos that you know pair well with the T90. By the way, I haven’t got the T90 yet and, by now, I know that you are fond of the HD 650. So if you think I can get what I am looking for with the HD650, I can go for this one as well if you think it’s more forgiving on amp+DAC synergy. The reason why I didn’t consider the HD 650 in the first place is that I am somehow used to Grado and I think H650 is on the extreme opposite side of Grado sound signature. Sorry for sch a long winded comment lol.

            Cheers

            • Reply July 29, 2016

              dale thorn

              For a headphone like the T90, if you do get a decent tube amp, you could probably use a DragonFly as the DAC. You might find a better DAC in the $2000 USD range, but below $1000 I wouldn’t bet on it. The amp will make the bigger difference.

              • Reply July 29, 2016

                JOHN

                If I can seriously get away with DragonFly as DAC, I could choose between Crack, RSA Raptor, La Figaro 339 and Woo Audio WA2. I have never heard any of them so I have no idea how better expensive ones are compared to the very affordable Crack. Any idea?

  • Reply August 1, 2016

    JOHN

    Any suggestion for me?

    • Reply August 1, 2016

      Lieven

      A DF DAC for a tube amp? Sure! I also advice the HERUS or the HD but there are plenty of others as well.

      DF Black + 339 + T90? Done. 🙂

  • Reply July 27, 2017

    julien-hifi

    Hello Lieven,

    You got me convinced and i bought a herus+ with the bakoon hpa-01m, and it’s quite special.
    I have 2 HP today, mr speakers ether c1.1 and hd800s. Both really go well with the current output, i was bit worried for the sennheiser, but also a good pairing to my ears.
    After reading your reviews, and that the bakoon goes well with Audeze (but i have a problem with their weight) and hifiman, i soon will get the edition x v2 to try as well, should be interesting.

    So my question is this, am looking at a different type of sound and also make use of a balanced output. So after some research, the cavalli liquid carbon would be my choice. I will try using the herus+ as a DAC.

    Did you try it with one of these HP and could give me some insight compared to a bakoon sound?

    Thank you

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