I used to use a REGA EAR with my AKG701 and it was pretty good. I now use a Cayin HA-2 head amp for the AKG's and it's a revelation. Sounds just gorgeous. The AKG's are excellent headphones, but slightly dry, so the tubes from the Cayin helped flesh out the sound a lot.
Agree with Mcrespo71 wholeheartedly - nothing really more to add to his comments, so I won't

. I have this combo as well and absolutely love it. Come to think of it, I will have a go at commenting

. . . this pairing exhibits terrific bass, deep and quick; it seems that the Cayin has an iron grip on the drivers. Lastly, and the soundstage is rather impressive for cans and is noticibly larger vis a via all other parings I've come across (and own).
As has been suggested, check out HeadFi, and do an appropriate search - a wealth of good info. Highly recommended.
Cheers,
Garry