[JCD]

I think the AKG's will do just fine with your receiver.

One of the guys in my office uses a Marantz CD player at work, but bought a Darkvoice 336 headphone amp for home. He brought the amp in and I did a side by side comparison. Now, it's not scientific by any stretch, but I level matched the two as best I could and played a Jazz CD and Rock CD powering my 701's through the Marantz CD player itself and the headphone amp.

Me, I couldn't really tell a difference. I'm sure my ears aren't all that great (worked too many rock concerts during college), but I don't think I could ever tell you there is a night and day difference between the two. Now, my office mate said he thought they were close, but he thought the dynamics were a little faster with the Darkvoice. He of course has $250 invested in the thing.

OK, so my bottom line is as follows:

1. I think the 701's are a great set of headphones -- but then I own them, so I MAY be prejudiced (you can see my comparison to the Senn 650's here).
2. I don't think you'll get the full benefit of those cans straight out of a portable player like an iPod, but it will still sound good.
3. I think, at least for most people, you'll be just fine listening to them out of a receiver.
4. Even though I didn't really hear a difference, I'm sure someone with a trained ear will hear a SUBTLE difference with a quality headphone amp.

Good luck and happy hunting!