Looking for a great tube headphone amp

The two moderately priced tube models I auditioned for my HD600's were the MF X-Cans v.2 and ASL MG Head DT. In my opinion, the Musical Fidelity beat out the Antique Sound Labs for neutrality and dynamics, as well as bass firmness. It doesn't, however, sound particularly "tubey" (as opposed to the ASL), if that's what you're after. There were some aspects of the EL84-powered, transformer-output ASL that I slightly preferred in terms of spaciousness and liquidity (also jack and pot quality), but in the final analysis, it was just too colored and slow compared to the 6922-powered, output-transformerless MF (which was used alone - not with the X-PSU upgrade AC transformer). I'm a tube fan, but this ASL sounded excessively old-fashioned to me, while the MF was natural, articulate, and extended (and featured better casework). The MF adds a pair of loop outputs for signal pass-through as well, making it easier to integrate into systems where line-outs are at a premium for recorders, processors, etc. Guess which one I bought? As for the 'phones, I tried the Grado RS-2's, but found them bass-heavy, lacking a bit in clarity, and uncomfortable (just plain heavy) compared to the HD600's - whose prodigious resolution admittedly does come at the expense of a little thinness.

Interesting to see that I'm the only one here who didn't find the ASL MG Head DT to work to his satisfaction with the HD600's, hearing a consistent sonic signature across all of my sources that comparision revealed was endemic to the amp. For the record, since some of the above folks mentioned this, I did invest in a new pair of JJ EL-84's and burned them in well, but didn't find the sound a whole lot improved. I returned the unit for a refund, but I currently have no use for the upgraded tubes, which have a long life ahead of them...offers, anyone?

Gilbaino, it sounds as if we basically agree on what we heard, and just have different preferences. In another thread a while back, someone posted that the current-production MG Head DT now eschews the use of an output transformer, like the X-Cans (but I can't see any differences on ASL's website). If this is true, it might well be that factor, and not the tube type, that was responsible for the ASL's more rounded sound - anyone with knowlege of this alleged development? As for the X-Cans themselves, I have to add that I've been very disappointed with the quality of their unusual, sealed output jack design - I've gone through two of them so far, and still can't get a reliable connection with any of my 'phones.