i have the Fiio combo and K702s. The 702s are new (2 weeks old) and still being burned in (im new to this too) but i find the combo to be petty good and great for the price, though its no where near as good as the setup i auditioned the 'phones on in the store (i didnt ask or check, but i assume that was at least $500 or more of equipment). The only issue i have is that they suck the "soul" out of some songs with this set up. That is to say that they sound great, with clarity that i have never heard before. But something about them reduces the emotional impact some songs have on me. the opposite was true with the other set up, which made my hair stand on end. that might be because I haven't finished burning them in though.
Over all though i am very happy with the Fiio set up, and could recommend it for low budgets. I have a CD of "passion" by "eminence symphony orchestra" it is my favorite album, and i was at the concert it was recorded at. I have listened to that through any number of speakers and headphones (though not many very good ones TBH). The Fiio K702 combo sounds EXACTLY the same to my ear as the live concert, i totally wasn't expecting that and it really blew me away. After years of listening to the same songs in different "flavors" through different systems i felt like i was back in singapore at the concert, i am still really impressed whenever i listen to it. othe things are less stellar, simon and garfunkle sound a bit "meh" but on the whole its a solid set up in my opinion.
All that being said, im new to this, so i could be WAY off. Sound is a very personal thing. Hell, i have a set of cans i LOVE, they are made by TDK and cost $30. Most people on here would utterly hate them, but i really like them. To me sound like an aural version of being wrapped in a nice warm blanket on a cold night. to others they would sound utterly terrible. So rather than asking whats good it might be a good idea to think about how you want the 701s to sound and ask what amp will do that to them. Better yet see if you can try out the amps you want to try at a store somewhere if at all possible, you can see if the Fiio is for you or not for example.