I've got the MK I, but the specs look the same. I don't have much to compare with, but it sounds fine, and the same as the headphone output of my hi-fi amp. The hi-fi amp has a very high output impedance, but my headphones have a flat impedance vs frequency curve, which is why the V-Can sounds the same, I think. I do think the "This means it will drive any headphone available with ease." sentence on the web site is a bit misleading, because the V-Can doesn't have a particularly strong output drive - if you like to listen loudly with high impedance headphones, I would not recommend this amp.
The V-Can has a 5 ohm output impedance, which is not too bad, but is not considered low enough for the best quality with low impedance headphones. I.e - using the 1/8th rule, it is best suited for headphones of >= 40ohms. The 5 ohms impedance may be particularly unsuitable for some very low impedance IEMs. (and this is another reason I think that sentence is misleading)
I think it could be a bit overpriced now, considering the competition.
Greg.