I think the part where Lieven describes the technical aspects of the sound are spot on and I wholeheartedly agree. Very low noise floor, very clean sound, very black background, clear and distinct instrument separation — all these superb qualities as long as you’re on the low gain setting. I also agree that while the bass reaches down very low (for a portable amp), it lacks impact and punch. Asking for more impact and punch is not the same as asking for a bass boost. You can have a good neutral bass presentation like the O2, but with a stronger impact when the music calls for it — this is what the O2 is missing. The mids are moderately thin in comparison to amps like the C421 or the Fiio E10/E11/E17 that Lieven and me both liked, and some of my friends also reported the treble to be a little bright though I didn’t feel this to be the case. For the most part, I think L and me are hearing the same thing.
Most people who listened to the amp do agree that the O2 is a very clean sounding amp, and I think that’s mostly to the black background that is indeed impressive for a “portable amp”. But the issue here is that it is not a portable amp. I attempted to use the O2 as a portable amp a few times, but I ended up using it only when I’m sitting down in a coffee shop writing an article from my laptop. I would hook it up with a good USB DAC and enjoy a relatively good sounding set up without needing an AC plug. The O2, both the JDSLabs and the Epiphany was very quiet and I can either use it with an IEM or a moderate-sized headphone.
Most of the other time I spent with the O2, I tried using it as a desktop amp by connecting it permanently to the AC adapter. But it doesn’t seem to work very well for that either. The chassis is too light and it moves around a lot. The input and output connectors would be better if it was a pair of RCAs and 1/4″ TRS for desktop purposes, and the DC connector placement on the front panel makes for an untidy wiring. Little things that makes it less ideal for a true desktop amp, but that’s what I mostly use the O2 as. Even then, I keep on missing a more powerful impact for the bass and so I ended up going back to the Schiit Asgard most of the time. At $249, the Asgard is not technically as clean as the O2, but it behaves and overall sounds like a bigger amp than the O2.
I enjoy the black background of the O2 very much, and for the majority of people I think that aspect alone is what’s going to draw them to the O2. The Cmoy and the Mini3 amps that NwAvGuy tries to beat with his O2 don’t come close to reproducing this deep black background, and I don’t think any other portable amp does either. A good black background would lead to better sense of clarity and superior instrument separation as I’ve mentioned before in my other reviews so indeed this is very good. If that’s what NwAvGuy is trying to accomplish with his design, I have to congratulate him for achieving that. Very clean sound, very black background, period. But I guess the advantages stop there.
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