I picked up a X-Can V3 and X-PSU for my girlfriend over the weekend, and I have to say that the X-PSU makes a huge difference compared to the puny wall-wart. We tried a number of headphones with it over the last couple of days including the Sony CDR3000s, and there was absolutely no hiss or noise with any of the phones. In fact you can turn the volume all the way up and it is totally silent. The X-PSU was partly responsible for this as there was a little more background noise with the wall-wart. The combination with the Sony headphones is a little bright, but very fast and articulate. The detail is very good, and the soundstage is the same huge one we all associate with the Sonys. The only issues that I felt were relavent was the bass being a little laid back and not as deep as I've heard. 6922 tubes being readily available means the amp can be tuned somewhat.
Having said all this, the combination of X-Cans/X-PSU is approaching $800 (although discounts can be had), and in that price range there is some serious competition. I went with this combination partly because of the aesthetics (we are a square box couple), partly because we plan on getting a tube buffer and because of the good, if not the last word in, sound quality.
I definitely think there is some resistance here to mainstream gear, but some of it CAN give specialist manufacturers a run for their money.
