I'm just about to make the plunge, and have read many-many posts over many-many hours trying to decide on a headphone rig. I've decided on the K702 and just need the final decision on the amp. I'll be using the DAC in my Tact 2.2XP preamp.
I've narrowed it down to two choices:
Matrix M-Stage - $270 from coolfungadget
Audio-GD C2 (includes Earth op-amp) - $405 from Pacific Valve (http://www.pacificvalve.us/ADGDC2C.html)
I won't make use of the ACSS input on the C2, as I will feeding it directly with RCA cables from my preamp, so this might be a bit of a waste. Is the extra cash for the C2 worth it? The C2 seems to have a bit more rated power at 60 Ohms (1W for C2 vs. 400mW for the M-Stage); does this make any real-world difference in powering the K702 which are known to be difficult to drive? If you had to decide between these two irrespective of price, which one would you choose and why?
Thanks in advance.