Just thought i'd throw this out to anyone looking at different amps for these cans. I have an Asus STX which i've been using as a headphone amp and been pretty happy with them so far. However, i have been reading alot of the "vintage amp" thread and decided to see if i could improve on the sound without spending alot.
I picked up an old Sansui amp. Signal route is: stx rca out > sansui aux in> sansui headphone out. Benefit of this is i still get the stx dac being used, and i get the power of the Sansui amp. Not going to go into graphic detail here as anyone can read the thread, but in older amplifiers, the headphone jack is hooked directly into the power supply just as the speaker outs are. Thats not really done today. The result is very very good sound with lots of power to spare to run harder to drive cans .My Q701's sounded awesome before, but now have a bit of added warmth and lots of power to drive them.
I spent a total of $50 for the amp by the way. Pretty confident they would run even the hd800's with ease and sound great. Thats just about the cheapest headphone amp you could buy. Maybe a tad bigger than most, but if its just sitting on your computer desk who cares. If anyone out there has done something similar please share what your using.
This is partially correct. Usually the headphone out is wired to the speaker outs with a resistor in between. This raises the impedance of the headphone out which makes it more suitable for high impedance cans. That's not to say it won't work with lower impedance cans though.