Musical Fidelity X-Can V3 would be a good consideration. Very nice synergy w/ Sennheisers. Upgraded power supply is a definite plus.
Ultimate headphone amp?
What are some of the better headphone amps out there for use with HD650's? I have had the Earmax before which was very, very enjoyable. Either tube or "warmish" sounding solid state will do. I have read reviews but not listened to Sugden, SinglePower and RudiStor. I have tried Headmax before but did not like the slightly cold/sterile sound, I prefer the slightly "tubish" or "euphonic" with "richer harmonics" sound. What else should I consider?