Ultimate headphone amp?

Musical Fidelity X-Can V3 would be a good consideration. Very nice synergy w/ Sennheisers. Upgraded power supply is a definite plus.

The Single Power units can be tailored just by changing tubes. If you want lush..throw in lush tubes. The 6sn7 should give you what you crave.Or try some of Mikhail's tube inserts and experiment with many different types of tubes. You have to ask yourself. Do you want a head-amp that is versatile in sound. Or one that sounds the same no matter what you throw in the sockets. I like my head-amp so much I use it as a preamp. It's the quietest tube component I've experienced personally at home..no hum, no hiss, no snaps, crackles or pops. These units are terrific tubed preamps by the way. Definitely one of the best kept secrets in audio.

Good luck with the hunt

Cary 300 sei integrated has an hp jack and cut-out switch for speaker outs so you can use it to drive your entire system if need be. The 6SN7s and 300bs give you lots of rollling options.

We just compared the Consonance Cyber 20B (basic version) to the very highly regarded Ray Samuels Raptor. The Ray Samuels is almost twice the price. We used the sensational $400 AKG's. The Consonance had better tonality, more musical while still being more open and more transparent. For a little more money, you can buy the model 20 with separate power supply. Consonance makes great built and great sounding products. Bargains for the price.

If you can find a Berning MicroZOTL grab it-excellent match with Senn 650's.
Joe

Cary 300SEI. The phone jack connects directly to the transformers!! No opamp involved here. I used this combination in the past.

You should look at the Ray Samuels Emmeline II Raptor. I did not like the Sennheiser 650 at all until I got that amp. You can tailor the sound a bit by tube rolling and Ray is very easy to deal with. The Single Power has bit more tube lushness than the Raptor. You can read reviews of these products at
http://headfi.com/

Hifi+ reviewer-decidedly not an enthusiast of headphone listening, really loved the Stax offerings he reviewed in a very recent issue...System series two w/ energizer, I believe. Very expensive, and maybe a bit terrifying. Sounds like you have to get strapped in, with a complimentrary bit to keep you from biting your tongue. How real is that!

I used only headphones for about htree years and tried most of the upper end amp/phone combos either through friends, meets, or home audition.
The Singlepower amps I heard or owned were head and shoulders above all the others I tried. I ended up with a full blown SDS-XLR two box 150lb balanced tube amp from them. When used in combo with the HD650 and balanced Zu mobius cable the sound was stunning.
Check out www.head-fi.com for more amp info.