I've been using a pair of HD650s for a while and really like them. The bass has plenty of weight but isn't overpowering, mids are clear and strong and the top end is light and musical. They are also very comfortable, I can listen for a couple of hours and have no problems at all.
Turntable
Toshiba SR-370/Mission 774/Van Damme cable with MS Starline plugs/Ortofon Quintet Black
CD
Cambridge CXC transport/modified Musical Fidelity X-DAC/modified Musical Fidelity X-10 V3 tube buffer
Network Player
Cambridge NP30
Amplifier
Denon HA-500 head amp/Nakamichi CA-5E pre-amp/Chinese passive RVC/Proton AA-1150 DMC power amp
Speakers
Mordaunt Short Signifer on original factory stands
Cables
Mogami with Rean Neutrik plugs/NVA LS5
Headphones
Sennheiser HD600/Sennheiser HD650/Koss Pro4 AA