Reports from HeadFi say the Q701 sounds a bit different from the K701. Claims from HeadFi are that the Q701 has more bass, and that really has me thinking. I am almost 100% content with the K701 save it's missing a little something in warmth and low end, I keep wondering if the Q701s fix that problem. My K701 isn't uber treble happy so I am quite happy with it.
And yes edsamac, the soundstaging is for real. These have the best soundstage and separation among all the cans I own and have owned. In fact, it's the soundstage that prompted me to get the Mios in the first place (well, that and, well, Mio). To beat these you really need to start going into Stax and HD800 territory.