suggestions for a headphone amplifier

IIRC, Moth headphone products are now sold under the Eddie Current (cute, huh?) name. I think there is/was in the under $500 range. You may want to try headfi.org for used amps and reviews of virtually all hp products. And Rocco, if you can stretch your budget to about $700 you should be able to find a used Audiovalve RKV MK2, which is an OTL amp that to my ears has more punch and more definition than the ASL amps.

Daltonlanny -

IMO the Senn 650 has a smoother, richer midbass and better balance than the 600. I find the midrange of the 650 is flowing and the highs are smooth, with a slightly dark presentation. To me, the sound of the 600 is generally similar to the 650; however there are some slight differences - the 600 treble is grainier, the midbass is boomier, and the bass is less robust. I also find the 650 to be more comfortable than the 600 and I have less listening fatigue with the 650.

Also, the MF X-Can does not lack power to drive the 650.

John

Thanks Johnrob!
Lanny

Another vote for the Antique Sound Labs Head MK III. This is a fine, economical intro to the magic of the SET experience. I thought the MF X-Can perfectly capable, but the ASL added that special quality of living air; with a marvelous hang-time for a note's resonant fade-out ...

Group,
It's one day later and I am savoring all of the suggestions.Some additional snooping on my own has uncovered Audio Valve RKV MK11, Singlepower offerings, enen a Gillmore new offering or the established Little w/ dedicated power supply. In some instances my 500.00 dollar ceiling is blasted, though I knew that would occur anyway. Headroom amps are for the most part unavailable for now, and I guess that their new line won't show for a month or two. Looks like there's a ton of great product out there. Tough choices!!!!!!