I agree, the Q701's are harder to drive than the Sennheiser HD 650's, the volume knob needs to be about another notch up for the same output. Nick

The HD 650's were dull and lifeless with too much uncontrolled bass, they felt as if I had cotton wool in my ears. The sound stage was really closed in as well. This of course is on my set-up and my experience with them, I've just sold them on and was really disappointed after reading such good...

I listen to my Q701's through my Nuforce UDH 100 Dac/Amp, fed by my iMac .I am really pleased now I have done the bass mod they sound fantastic with all types of music. Just sold my Sennheiser HD 650's as the Q701's beat them on all fronts. Nick