I can answer #2: It can drive an HD700 to certainly louder than I'd want to listen to. Listening volume is under 50% for me. As for 1 & 3, it's been a little too long since I've used my V10, but from early impressions I don't feel it matches that SQ. I haven't heard the V20 so I cannot speak of the direct comparison. It should have no issue being connected to an active speaker using the LO.