I know I use my A40 and mixamp for MP/soundwhoring/when I need a mic, but I've been using the HFI-780 with the mixamp for everything else. I really, really hate using the A40 now unless I'm playing a shooter. The difference is ridiculous. I can't imagine what it must be like for the really good headphones. (I got the A40s and the mixamp before I really understood anything about audio. Regretting the A40 purchase a bit, but definitely not the mixamp.)
Yep same story with me and my X41s and D2000s a while back.