Can an Ibasso D6 even drive a K702 to 100%? I never heard of any portable amp being able to do that if that's what was used. Of course they should still sound good. One could probably get an idea if they'd like the K702 when using just an E5..ok maybe not! Years ago I attempted to drive the K701 with portable amps and that's just a huge mistake.
It all comes down to preferences. Both headphones have things I love and hate about them. It seems like it'd be impossible for someone to like both of those headphones!
The K702's soundstage felt so abnormal and it was so huge that it felt as if background details got lost in it and felt somehow too distant. At times the mids actually felt recessed, but were not. Everything else I loved. They were kind of bright, but it didn't bother me. I actually am one of those weird people who prefer a thinner sounding headphone. If I had to pick between the two I'd go with the HD-650, but I do prefer the K701 overall in most areas, but it's soundstage and distant mids ruined it. At least the K601 got most things right, but it isn't as clear or detailed.
HD-650 I never loved, but it's female vocals are what made it great to me. I hate nearly everything else except for it's detail. Sound was fairly clear too, even more so than the HD-600. I returned the HD-650 today since I hate it's bass and not because it's bass heavy. During some songs it felt totally congested and muddy at times. Acoustic Guitar music sounded bad on the HD-650 compared to my DT-880 and old ATH-AD2000.
I think there's no perfect headphone! I was going to exchange my HD-650 for an HD-600 but JR.com said they were discontinued! I won't go there. It was hard to return the HD-650 since I got it for so cheap. Crazy me actually prefers the DT-880. It's not that comfortable for me, but the K702 is. Strange.
What I need is a combination of a DT-880 and HD-600 
Edited by tdockweiler - 3/23/11 at 6:34pm