I suggest the Sennheiser HDR65. I bought some 120's for my wife and liked the no cord freedom despite the clunky phones. I then read some reviews and purchased the 65's, though they have been discontinued. (Tiger Direct has the refirbs for $100. )
The wireless phones themselves are very good quality-sound wise- though not as good as the best. However,they have their own amplifiers, somthing that I had not given sufficient thought. The amps are pretty good- though again not as good as the best, yet better than the uual receiver headphone output (HK). The real wild card is the FM reception for the phones. At best it is a little noisy-at worst it is unlistenable. Trial and error with location is the only alternative.
Regards,
Sam