I've listened to the K701's with an Arrow amp quite a bit, actually. It works/sounds really good. At *really* high listening volumes, the bass clips a bit, though. But you really have to pointedly turn things up to hear it. But all around? It works real good with the 701's. I'm currently using a 3G Arrow amp, which has a slightly different bass boost tone compared to the 4G ... bit more "thumpy" and tight ... and this servers the 701's *very* nicely as, I think they are sort of bass anemic, myself. But that's just my take on things so grain of salt and all ...
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Of course, the Arrow is not an ideal solution for the AKG 701's ... but for the record? It will push them to pretty nice levels.
Read more, here...where I talk a bit about the Arrow and full sized cans:
http://www.head-fi.org/t/538016/review-the-headstage-arrow-he-portable-amplifier
Rock.
j.