I'd like to chime in with a few impressions and opinions on the iCAN. I mostly agree with Nirmalanow but there's some other stuff that a prospective purchaser might like to know.
Just some background: I listen to CDs and LPs exclusively, no real listening via computer and no high rez so I'm real old school. I have WooAudio WA6, Headroom Total Airhead (battery only) and DIY class A headphone amps. My cans are a BeyerDynamic DT660, Grado 325i, woodied cups and large bowls, and a recently acquired HiFiMan HE-4. A BeyerDynamic DT880 (600 ohms) is going to be up for sale shortly.
I paid $266 including shipping from Georgia to Texas. It was nicely packed. Once unpacked, I did struggle a bit with the wrap-around packaging of the unit's box. In frustration, I just tore the packaging apart. Should I ever re-sell the unit, that item will not be part of the sale, lol.
The build quality is quite impressive at any price. It feels solid and heavy, there is no wasted space, it means the business.
I would characterize the sound of the amp in the "direct modes" as very competent, nice and airy, there's no doubt that this is a solid state amp in that it seems neutral and clean. A friend built me a solid state class A headphone amp years ago and recently updated it with an alps volume control and a low/high gain switch. The two are very much like each other in sound. A comparison between the iCAN and the Woo points up some expected differences. The Woo sounds rounder and warmer, more enveloping, a little more bass, euphonic, just more pleasing. One aspect that surprised me was the Woo was able to exhibit layering front to back that the ICAN could not, as in the soloist standing in front of the band/orchestra and being separate from them. One must take into consideration that the Woo, with stock tubes, retails at $620 plus shipping and with the fancy tubes, totals out at $797. The differences between the two amps are not vast but I noticed them right away. The iCAN, however, has a build quality very similar to the Woo and that is high praise.
Some observations about the operation of the iCAN:
The unit is very small, portable like, which makes everything on the unit even smaller. The volume control is a bit stiff and there is not much range of volume settings available. With the 660, a very efficient 32 ohm can, 9 o'clock is really loud. Likewise, with the 325i, 9:30 is about maxed out. The 600 ohm 880 goes to about 10 o'clock and the much more inefficient HE-4 maxes out at around 11, and, no, not THAT eleven. With the stiffness of the control coupled with the limited range of motion for comfortable listening, getting just the right level is a challenge. FWIW, this is one of my pet peeves with most volume controls, they never use the range of motion that should be available. I think part of that stems from the manufacturer wanting to impress the potential buyer with how little adjustment it takes to play really loud. This usually provokes the naive belief that the unit is so powerful you can only turn if up a little bit to get really loud. Oh, well, in this instance, the iCan is no different than most other amps. But, speaking of power, it had no trouble powering any of my cans, even the notorious planar magnetic.
The lettering on the unit is, consequently due to its small size, tiny. I pretty much have to memorize the positions of the Xbass and 3D switches in order to operate them. I don't use can amps as desktop amps which means I'm probably ten feet from my units. The other problem is that they are positioned counter intuitively. I would like the three position switches to function similarly but the Xbass is, from top to bottom, direct/three dots/one dot. The 3D switch is three dots/direct/one dot. I keep the provided cheat sheet handy so I can check that I have the switches in the positions I desire. I'm not sure why the manufacturer designed it like that. BTW, the unit is "on" all the time until and if you unplug it from the wall. It never gets more than slightly warm to the touch (good) and the wall wart is a purposely low noise unit (also good). BTW, I've had the unit plugged in 24/7 for over two weeks so it "should" be burned in by now. I've had no reason to use the rear mini-jack so I won't comment on it.
Back to the sound:
I like both the Xbass and the 3D capabilities. With the Xbass switch in the one dot position, this seems about right for the bass shy Grados, three dots can be a bit much unless you want to have too much fun. The 660 has basically a neutral mid bass (unlike the Grados) and can benefit from the three dots much more. The HE-4 doesn't need a bass boost (smile). With the 3D switch in the wide (three dot) position, it's really a bit much with the Grados. Remember, I have the G-Cushions which already widen the soundstage. The 660, a closed headphone with superior isolation but with a surprisingly good soundstage, does benefit from the widening. The HE-4 I find a little restricted as to soundstage width so it benefits as well. The other feature of the 3D position seems to increase the volume slightly and there also seems to be a brightening in the upper midrange. This is a good thing on the HE-4 (for me) but can be too much on the 660 and 325i, both being rather bright cans to begiin with. The one dot position of the 3D switch is a mystery to me. As an old timer, I remember FM stereo tuners with a blend switch. It was used to reduce separation in high frequencies which made noisy signals more listenable. That's what the one dot sounds like and very similar to the crossfeed circuit in the Total Airhead. Frankly, it makes the sound duller. I don't like this position so I don't use it. The reviewer seems to think that reducing the separation enables the listener to sort out complicated music easier. I would opine just the opposite. Jamming music together does not make the individual parts easier to hear, it makes it harder. All IMHO, of course.
I'm not a big "graphs" fan when it comes to headphones . I've seen too many headphone graphs that, in my opinion, don't match up with my ears. But amps are different. I would love to see some frequency response graphs on these two switches/positions. The Xbass is not a typical bass control where most of the boost occurs around 100Hz. It sounds more like a 50Hz boost and this is good because it doesn't muddy up the mid-bass. The 3D three dot position does sound like it's affecting the frequency response and I'm curious to see what that would look like. The real mystery of the 3D, however, is that I hear, as does the original reviewer, the soundstage spread out left and right. Very interesting and worthwhile on the right can.
I'm not a writer (no sh*t) and this is my first (kind of) review. Nirmalanow is a very good writer, organizes his thought well and covers a lot of ground. I just wanted to give a little less of a fan-boy look at and listen to, this good and interesting headphone amp. I think it's certainly worth the money (I bought it before I heard it) and I'll probably be keeping it. Folks with cans that are less bright than mine, and that would be many, will benefit from this amp even more than I have. As the reviewer points out, most cans do lack that bottom octave of bass that gives us so much satisfaction when we hear it on loudspeakers and/or subs. I also think that, in general, closed cans can benefit from the 3D effect by widening the soundstage not to mention those open cans that can(!) seem a little closed in. I think the iCAN is a winner and I hope this gives prospective buyers an even better idea of what they might be purchasing.