Mind sharing some impressions with the HE-6, as somebody had some problems with it, but you didn't?
For clarification, there are a few people in this thread that have not had issues with the HE-6. There was only 1 issue, which appeared to be an electrical issue either in the house or with the unit, as it was purchased in the UK but used in the US:
House electricity is solid. This unit is from the UK and I'm using it in the US, so the one thing I had to do was change the 3 pin power cable to a 2 pin power cable. Maybe that's the issue, I'll try some different cables or use the 3 pin with a 2 pin wall outlet adapter?
As for myself, I don't feel as comfortable evaluating amps/pre-amps as much as other equipment because to me, the mark of a truly great amp or pre is that it doesn't sound like its there. DAC's and speakers are easy to compare because you can hear what is there and what isn't, but I'm pretty firmly on Team Neutral when it comes to amps, and I have a hard time explaining what isn't/shouldn't be there (this itself is hard for me to put eloquently into words)
All that being said, my history with headamps include: magni2 uber, lyr2, ifi ican, soundblaster x7 (combo dac/amp but I've also used the line inputs to test it strictly from an amp perspective), ifi ican pro, naim dac v1 (combo unit i was testing). Not a huge fan of the schiits, and I got rid of those pretty quickly after I bought them. The ican non-pro has been driving my office rig consistently with my DT-990's, HE-400S's, HD 600's. For about 15 minutes it even drove my HE-6's when I took delivery of them (it made sound out of them, but with everything CRANKED it just lacked authority).
Setup consists of PS Audio Directstream Junior balanced out into ican pro into 4 pin balanced cable to HE-6. I occasionally listen to my turntable through my pre/pro and into the ican pro using the rca inputs - works great, but I prefer listening to my vinyl through my speakers. I also listen to movies (SE out from my XMC-1) late night through the headamp so it doesn't keep people up, and this pairs great with my DT-990's for some great action movie sound and explosions. I also tried the single ended into HE-6, but it just lacked that something special that the balanced offered (a bit of control, a bit of depth, maybe a bit of gusto - hard to put into words, I just prefer the balanced out to my HE-6's)
As for the ican pro and the HE-6: its great. Granted, I've never compared it to anything else (just because I don't have access to anything else even remotely powerful enough for the HE-6). But I think I know how these monsters are supposed to sound, and the ican pro drives these with authority, control, and finesse. It is clearly the best headamp I have (I did a massive comparison a few weekends back with all my cans, and they all sound the best on the ican pro).
In terms of loudness, I keep the gain in the middle position, and the volume knob never goes past noon. But overall volume is just part of the story, and I find the ican pro deftly handles strong percussion, the earthquake lows and striking vocals without flinching. My go to test CD is this Chesky album (specifically track 23 and 29). I also threw in some Lemonade, Life after Deathstar, and Tennyson Like What.
https://www.youtube.com/watch?v=GO4YDe073TU&list=PLdZhik4dyFHr4kncCtr024E2IfP330dP2&index=23
http://lifeafterdeathstar.net/
https://soundcloud.com/tennysonmusic/likewhat
I haven't really gotten into all the "features" of the amp like the 3D stuff or the different tubestates. I do use the Xbass at 10hz, which gives a lovely little bump for the HE-6's (haven't really tried out the other settings, just on cursory glance thought the 40hz was too much bottom end for my tastes.
Downsides? Don't like that the volume knob controls the preouts (only tested the balanced ones). Just wish it acted as a balanced pass through so I could fit this in between my DAC and pre/pro. It gets warm, but not hot. Also the front panel is crowded and confusing. I know they want this to be the kitchen sink of headamps, but come on guys: who is running dual 3.5 or 6.3 jacks to get balanced to their headphones? and 3 pin balanced? for headphones? never seen it
TLDR: tastes great, less filling
If anyone has any questions, I'd be happy to answer to the best of my ability