The Rx’s sound stage is pretty wide and there’s a good amount of air around the instruments. Not that it’s an overly airy amplifier though, everything sounds very coherent. The Picollo doesn’t have this spacious feeling to it, at least not as much as the Rx. Detail retrieval on both amplifiers is very good and they both have great clarity. The Picollo to me has the edge on clarity though and its background is even blacker than the Rx’s. Both amplifiers are very dynamic but here the Rx is clearly the winner, same goes for speed. In other words, dynamics are really good with the ALO amp and it’s the faster sounding amp of both.
The Rx’s bass is just right for me: it’s not a bass head’s amp but it isn’t bass shy either. It’s right in between and it has a nice punch, good depth and good body. Bass is tighter and faster than Picollo’s bass but that last one has slightly more body and impact to it. I really like both types of bass and it basically comes down to the type of music I’m listening to and the quality of the recording. It’s not that the bass difference between both amplifiers is huge but the differences are clearly there.
The mids section is where the biggest difference between both amplifiers is. The Rx’s mids have more body, are more detailed, smoother and have more air in them while they kind of sound tighter and more basic on the Picollo. They just have less timbre than on the Rx. It’s clear the Rx’s mids are more musical and flowing or smooth as you might call it. At the same time there’s so much happening that I sometimes find the mids to be more fatiguing then on the calmer Picollo. I do prefer the mids on the Rx but I can listen to the Picollo for longer periods it seems. The Picollo from its side, focuses more on the upper mids making them sound more forward then on the Rx.
Treble is fairly extended and is nicely sparkling. It’s never bright or harsh and it’s got good detail. Just like the mids the treble has an airy feel around them. Picollo’s treble is comparable but the mids here have a bit less air and just like the higher mids they’re more forward sounding. Overall that makes the Picollo the more forward sounding one. Picollo certainly isn’t an aggressive amp but it do is more aggressive in the higher mids and treble than the Rx is. I should really call it more “pronounced” rather than aggressive. You’ll mostly notice that with guitars and vocals.
The Rx produces the smoothest and most coherent sound of both amplifiers. Bass, mids and treble just flow smoother into each other than on the Picollo. On the Picollo the bass, mids and treble are more separated from each other. Both amplifiers sound great though and our review of the Picollo was a very positive one too. The amps just sound different and I found myself switching back and forth depending on the song playing on my DAP.
Nathan would call this the “Meh part”. I call it room for improvement
Besides the two earlier points about the placement and size of the volume pot, there are some other things that kind of bother me a bit. First off, I prefer the volume pot of the Picollo: it’s bigger, it’s wider and as a result allows better volume fine-tuning. On top of that Picollo has 3 gain settings.
In general both these IEM specific amplifiers are dead quiet and without floor noise but there always are exceptions. One of them is when you’re using a really sensitive balanced armature earphone like my Earwerkz Legend R. It is so sensitive that you can even hear hiss from the Rx. The question of course is whether this is the amps fault or the monitor’s. In most cases you won’t hear any noise though, and you shouldn’t worry about this at all. ALO tested it with a whole bunch of earphones, but they of course can’t test them all. I just want to point out that you will hear noise with a very limited number of BA monitors, that’s all.
Just a few more words on noise: some people hear it and some don’t. Those who don’t of course can’t see what the problem is and it most of the time leads to useless Yes-No discussions. In general I think consumers have become more sensitive to noise, especially with the increasing popularity of custom balanced armatures monitors. Nathan and I absolutely do not like gear that hisses. I myself always listen at very low volumes and it’s awful when you, during silent passages, can hear background noise. Gear nowadays (and especially at the prices they’re going for) should not hiss. Ever. But back to the Rx.
Matchability & Conclusion
The Rx paired well with all my DAPs but for some reason I liked it most in combination with the iBasso DX90 running the Lurker Firmware. The Rx, unlike the Picollo, doesn’t really manage to drive full sized headphones like the HE400i or other. It’s really built for IEM amplification but I did get good results listening to easy to drive headphones like the B&O H8, Philips L2, X2 and Beyerdynamic COP in example. I however wouldn’t buy it specifically for full sized headphones, focus on your IEMs. My favorite one was the CustomArt Harmony 8 Pro, which I find to compliment the Rx’s characteristics best.
Based on the description of the sound above, you should be able to judge if the Rx will compliment your monitors or not. You should in example opt for the Picollo if you prefer/need more bass body and the Rx would be ideal if you’re looking for a faster sounding very musical amp with great mids.
The Rx is great for use with IEMs: it is pocket friendly, well built, looks great and sounds really good. If you’re not very happy with how your source sounds right now or your DAP just isn’t powerful enough, the Rx might be exactly what you’re looking for. I’ve even been using it in combination with the Chord Electronics Hugo when I was listening to some of my IEMs. Not that the Hugo couldn’t handle it, but the typical Rx sound just is so nice to listen to.
The Rx is available directly from ALO Audio or via one of their dealers. Price is $299 or $349 USD. That’s only $299 for a very good sounding amp and you even get the $149 Green Line cable with it, that’s impressive. If you have a quality set of earphones you almost owe it to yourself to get them good amplification. For this price you should have been ordering it already!