ALO Audio Rx: Your IEM’s Best Buddy

Disclaimer: ALO Audio is a site advertiser. The ALO Audio Rx amplifier was sent to us as a review sample. In Ohm Image’s last podcast with yours truly we also talked a little about the new Rx and the Picollo.

ALO Audio – The Rx Story

We’ve been a longtime fan of ALO Audio and over the years we’ve done a whole lot of reviews of their gear. We liked some more than others but in general ALO has always delivered top quality products with great build quality and sublime sound. What more could you want?

That being said we haven’t reviewed new ALO gear for a while now, the last product being the Island. And that even was over a year ago. ALO is back now with the Rx and they have a whole lot more new stuff coming (like the gorgeous CDM!).

Unlike the old Rx, the new Rx is a portable amplifier built specifically for use with inear monitors. A lot of you will still remember the “old” Rx. Back in the days ALO was still working closely with Cypher Labs and the iPod + CLAS SOLO + RX triple stack was one of the first portable setups that gave you desktop quality for on the go. A lot has changed over the years; there are a lot more high quality DAPs on the market now and customers want to keep it small. The combo gave a lot of power and excellent sound. It powered Audeze’s without issue but the downside was the Rx wasn’t the quietest amplifier on the market for IEMs and very sensitive/easy to drive headphones. The Triple Stack however will always be a classic, there’s no doubt about it.

alo_rx_07

The New Rx

In 2009 Audio Line Out first introduced the Rx portable amplifier. The new Rx was redesigned for IEMs, and only has 0.002% distortion. The new Rx has several remarkable features:

1. The Rx employs a wide band integrated amplifier and push pull power supply.  Improved power filtering provides an extremely quiet supply and ultra-low noise floor.

2. “Huge dynamics are the result of our new 15 volt amplifier design.  The new Rx’s 15 volts give it plenty of headroom for the loudest passages to be reproduced wide open and without distortion”

3. “The new Rx  has super low output impedance. This allows it to deliver superb audio performance to earphones and more specifically, low impedance In Ear Monitors.”

The Rx, just like the CypherLabs Picollo is analog amplifier. When my first Rx arrived, I expected it to be a lot bigger but it’s about the same size as the Picollo and measures only 2.28×3.64×0.69 inches. A real portable amp, not like the old RX which wasn’t really pocketable. The new Rx has a limited edition nickel plated CNC’d aluminum enclosure but it in the meantime is also available in black. On the front of the amp you’ll find the 3.5mm in- and output separated with a bright orange LED. The volume pot is situated on the right of the input and is very small compared to a lot of other amps. Let me get back to you about it in a bit. On the back of the Rx you’ll find the micro USB connector and a less bright LED. I love the way the Rx looks and the two features I like most are the bullet hole style sides and the top plate on which you’ll find the Rx logo “engraved”.

The bright orange led in the front has a tube glow kind of color and with the holes in the sides it almost looks like there’s a tube inside. (see pics) What a design! Simple, small, pocketable and stylish. Love it. But back to the volume pot.

ALO Audio specifically chose a plastic volume pot instead of a carbon element pot: “A high quality conductive plastic element type potentiometer for extended life, high resolution and high reliability”. The volume pot is very smooth to turn and just wide enough to allow accurate volume setting but I do have a couple of (minor?) issues with it. First of all it is small, maybe too small. Compared to the Rx, the E12A and Picollo volume dials are huge but at least they’re easy to hold and turn. This brings me to my second issue: I don’t think it’s ideally placed. It’s located a bit close to the input socket and with the cable plugged in right next to it, it just isn’t very accessible. Besides that there’s a little channel imbalance like almost all analog pots have but at normal listening levels this shouldn’t bother you. The Picollo’s volume control doesn’t do that and it’s easier to reach as well. I hope they’ll take this into account if there is ever going to be a revised version.

The new Rx’s introductory price was $299 and it now goes for $349 for the Nickel version and only $299 for the black version. Accessories wise you get bands, a pouch, a Green Line USB cable and a wall charger. All that in a decent, nicely presented quality box. If you look it like that you get a lot for only $299, the USB cable alone costs $149 in the store just by itself!

Sound

All comparisons made below are to the CypherLabs Picollo as I see this as the Rx’s main competitor. I’ve been listening to a lot of high end portable gear lately with amongst others the Chord Hugo, the Bakoon HPA-01M and a whole bunch of (custom) inears like the Legend R and the CustomArt H8P. My ears have been really spoiled but listening to a simple setup like the iBasso DX90 in combination with the ALO Rx still sounds sublime each time I go back to it. The Rx has a pretty neutral tuning but it’s still on the warmer side. Don’t mistake this for being a warm sounding amplifier because it is not. The first two things that struck me when I first started listening to it were the bass and the lovely mids. In a lot of ways the Rx is comparable to the CypherLabs Picollo, and at the same time it sounds different.

It continues on page 2

ALO Audio Rx: Your IEM’s Best Buddy
4.2 (83.64%) 11 vote[s]

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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.

27 Comments

  • Reply May 13, 2015

    Lofthanza Art

    Nice review, thanx!
    i wish one day you could write an article about amping in general. What does it do? How much do different amps in different price ranges differ in sound quality? When would someone need an amp? And so on …
    For example i have the philips X2 and the ibasso DX90 and i use them together, i clearly dunno if i need an amp or not, coz the DX90 provides me with enough volume. Am i not doing the X2 justice with the DX90 alone? Should i add an amp in the chain? If yes, then please two questions, what amp would you recommend (under $300) , and what sound improvement should i expect coming from the DX90 built in amp?
    Thanks!

    • Reply May 13, 2015

      dalethorn

      Here’s a summary I wrote 2 years ago, and looking over it now it’s still pretty much accurate. There’s a LOT to this so go slowly….

      http://rockgrotto.proboards.com/thread/9303/introduction-portable-headphone-amplifiers

      • Reply May 16, 2015

        Lofthanza Art

        Thank you! A very helpful summary.
        should i understand that the performance of usb dac/amps usually degrades in higher volumes?

        • Reply May 17, 2015

          dalethorn

          There are many ways the sound can degrade, of course. Now the DAC is designed to send its output voltage into an analog amplifier, which may be built into the same enclosure as the DAC. If the DAC has one of those “internal volume controls” that’s controlled by the host computer, then all bets are off, because I can’t say what’s happening where. Today you could have a system volume control, a music player volume control, and a volume control on the amp – all 3 live at the same time. Someone will say “set two of them to maximum and the other you use to control the volume.” It sounds good in theory, but that’s no guarantee it’s the best method. You have to experiment. BTW, you can buy a combo DAC/amp in one enclosure, but the amp might be inferior to the DAC. Or you could buy the best separates, but they might have the wrong synergy. You can experiment yourself, or trust certain reviews. Whatever you do, if you buy a separate DAC and amp, get the best and the shortest interconnect cables you can find. Keep the contacts of the cables and the DAC and amp very clean. If you can, open the DAC and amp and make sure they’re clean inside. If they have removable internal connectors that aren’t permanently soldered in, you may want to clean those occasionally. If you can run your amps from a battery, by building a battery cage to get the right DC voltage, to replace a “wall wart” etc., that can improve the sound.

      • Reply January 1, 2016

        Traveller2225

        Hey Dalethorn I dont know why I didnt think of asking you about this question, I was considering the Alo RX IEM version for my Fidue A83 for my Hybrid in ears, but I also am going to be receiving the Sound magic HP150 which I got on sale for around the house and when I travel from CT to MA. Would this amp power and or drive them well ? or do you have a recommendation maybe a couple portable amps that I could pair wth the dx90 for the Sound magic hp150. thanks a lot for your times and happy new years

        • Reply January 1, 2016

          dalethorn

          I think the E12 would be good for having more reserve power for full-size headphones, since my headphones seem to “breathe” easier when they have extra power for dynamics. But the E12 is pretty much entry level only for sound quality – but then again, for portable use you might not appreciate the finer detail of the better small amps. The thing is, in most of the DAC/amp combos, the amp is the weakest link. The 2 best portable amps I’ve had are the Portaphile Micro and the Decware Zen Head, and you see the reason when you’re paying $400-$500 for a separate amp. But I still like the E12, especially for the form factor. I use mostly the Oppo HA-2 now, which is the same form factor, but it includes a DAC, and probably doesn’t have as much power as the E12. The E12 has been out long enough, that I wish FiiO would come up with a newer better version, with the same form factor, but a higher-fi sound. I also use the FiiO E17k now when my Oppo is down for charging.

          • Reply January 1, 2016

            Traveller2225

            Hey Yeah I can understand for the form factor and price. I do have some decent audio portable amps. One being the Meier 2move, and the other being ibasso pb2. I was leaning towards the pico slim or the Fiio e12A which is based of the off the E12diy edit. taking the most popular setup as far opamp and buffer and making an iem edit with the e12A. I am leaning towards that or the pico slim, because I use mainly IEMs away from my pc( earsonics sm64v2, fidue a83, and will use the 32 ohm sound magic 150).

            • Reply January 2, 2016

              dalethorn

              Last time I saw the Pico Slim it was very pricy.

              • Reply January 2, 2016

                Traveller2225

                Someone is selling on for just over 200 i believe. it is still pricey normally. I dont mind buying and or trading secondhand though.

                • Reply January 2, 2016

                  dalethorn

                  If it’s used or refurbished, then you’d need a paypal guarantee of satisfaction, and if it has a built-in rechargeable battery, you might need to replace that. When I sell used gear for example, there’s no returns, so you’d have to know what your options are….

    • Reply May 13, 2015

      Headfonia_L.

      thanks. Read Dale’s article first.
      Amps tend to get the best out of your headphone, “audiophile” headphones often need more power and current than DAPs can supply so that’s why there are amps basically.

      Not all headphones need them, but in case of the X2 you could expect more extension, and a tighter bass in example

      • Reply May 13, 2015

        dalethorn

        Definitely for the X2.

      • Reply May 16, 2015

        Lofthanza Art

        Thank you!
        No specific amp recommendation for the X2? Something i can use with the DX90. It can be portable or desktop, coz sound quality is what matters here, but budget is $300.

  • Reply May 13, 2015

    Brett

    Excellent review, as per usual!
    It would be interesting to see how this will pair with the new AK JR when it is released.
    Out of curiosity, not practicality, would it be able to power Grado P500’s as they are fairly easy to drive?

    • Reply May 13, 2015

      Headfonia_L.

      Thanks Brett. I don’t have the P500 so I wouldn’t dare confirm, sorry

  • Reply May 13, 2015

    jeff k

    i think it would be useful to compare the dx90+alo rx to the dx90 alone. why add an amp when the dx90 has one built in? especially in the case of iem’s, there’s no need for more power. so what’s the external amp adding beyond the dx90’s own amp? i’m not saying that there’s no case to be made, but i’d be interested in seeing that case made.

    • Reply May 13, 2015

      Headfonia_L.

      Sound quality is just better with more power. + With an external amp you could change the sound signature if you’ld want that

      • Reply May 13, 2015

        jeff k

        1. a comparison of the alo’s power with the dx90’s on various gain settings would provide useful context.

        2. so would a comparison of sound signatures.

        i appreciate being able to read reviews like yours, so i’m not trying to be negative, but to say what would make it even more useful, at least for readers like me. i think the comparison with the cypher is useful, as that’s a comparable piece of equipment, but the other competition to the alo rx is not buying any amp at all.

        • Reply May 13, 2015

          Headfonia_L.

          I see. We don’t really do numbers on HFN very often, besides if the Rx and DX90 numbers are public, you could easily compare them yourself 😉

          You won’t easily see comparisons of DAPs to amps anywhere, as they can’t compete in the currrent/voltage section

          Just my opinion of course

          • Reply May 13, 2015

            jeff k

            i can see the dx90’s output on e.g. high gain reported as 2.8Vrms and the alo rx’s as 15V [extreme value, presumably, not rms], but what i don’t know is how that affects the sound, especially listening through iems, not cans. unfortunately, most of us don’t have the opportunity to audition equipment, so we rely on the descriptions of others.

        • Reply May 14, 2015

          ohm image

          Jeff, I will be happy to supply RMAA and square wave measurements, but I’ve had some problems with RMAA recently on Yosemite. I had meant to publish all my measurements until this point but have had no end of problems.

  • Reply October 28, 2015

    BigC

    Hi Lieven, is there a desktop equivalent to this amp in the same price range you would recommend to power a Nuforce Primo 8. I’m currently running this iem straight out of a HRT Microstreamer and the headphone output is very noisy.

    • Reply October 29, 2015

      Headfonia_L.

      Maybe Fiio E12A?

      • Reply January 1, 2016

        Traveller2225

        I thought the Fiio E12a was a portable amp as well? I am actually deciding between the two amps. I use sensitive IEMs like the Fidue A83 and my will be using the Full size headphone soundmagic HP150 which is 32 ohms. Do you feel like if one was getting the Fiio E12a for 125$ would it be worth going up to the Alo RX Iem version performance wise?

  • Reply April 9, 2016

    just_pch

    How long is the battery life on the RX? Would you say it would be better to get the Fiio X1 + RX combo compared to an all-in-one solution like the Dx90 on its own?

  • Reply May 15, 2016

    Vaibhav Pisal

    hello headfonia,

    i am looking at one of alo amps for iems. how would rx compare to alo international plus only for iems if you tried both? is there a performance gap or both in same level? if performance is similar I might go for international plus.

    both are similarly priced but international plus is in warehouse deals so is likely used and no warranty. but it does have useful extras like power for full sized cans, dac and balanced out.

    also will international plus be able to power sennheiser hd700? for reference i recently used mojo and felt they needed more power. bass was not present as was with other easier to drive hps.

    but my priority is iems. for 700 i have rig sorted and have other things in mind.

    thanks in advance

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