M-stage is far more powerful. I will have an M-stage here sometime next week to compare, but the M-stage should have larger soundstage and more detailed/clearer/open sound.
The E10 doesn't have the biggest soundstage (when running 701s), but it is nice and smooth sounding. Most people seem to think the K701 is too bright (my Q701 isn't too bright IMO), so the E10 could pair well and smooth the K701 a bit.
E10 + E9 sounded brighter, more clear and open, and bigger soundstage than E10 alone. But E10 alone is a pretty good improvement over a soundcard.
Edited by chicolom - 12/10/11 at 3:20am