sweet, euphonic, reasonably powerful tube amp?

Circuit design is an obvious variant but apples to apples I have found that the EL-34's have a seemingly more inherent midrange richness than the 6550's or even KT-88's My experience is based on my last tubed monos, the VTL MB-125's which are 4 x EL-34's per channel and can do tetrode or [1/2 power] triode. They provide much of what you're seeking in tetrode but almost all you're looking for in triode. I can also second the recommendation for the older MV series CJ's, perhaps an MV-125 IF you can find one (I've had my eye out for one for awhile) or an MV-100. I went to CJ from the VTL's with Premier 12's right now which are using 6550's. Sound went from velvet to silk in the midrange (rich and creamy to less fat but more "zest"), bottom went from ballsy, fast and strong to even faster, a bit leaner, somewhat more defined, and the top end went from ever so slightly rolled off (but didn't miss it), relaxed and natural to considerably faster, more detailed and extended but with no hints of harshness or bite. Each sound is a new acquired preference but it sounds like the EL-34's meet your description better. VTL also makes an EL-34 based bigger pair of monos.. I think they're MB-250's or so ?? Correct me if I'm wrong. I know they made MB-225's that were strictly triode and used 6550's but they also had a tetrode/triode switchable one with the EL-34's too I think. Might be worth a listen.I've also heard great things about the Dodd 120 monos (again, EL-34 based). Good luck.

The gentleman who inquired about your room is, I think, on to something. You appear to be trying to use your amplifier as a tone control, and I submit that is the wrong approach. Instead, identify what it is in your system that makes the sound harsh and address that issue.

The room is the most important component. You may well be hearing the harshness of room effects, and I would strongly suggest room treatments. They don't have to look very intrusive. I had an acoustical consultant listen to and look at my room, and he recommended placing "BAD panels" (basic acoustic diffusor, I think it stands for) manufactured by RPG. They are not sound-deadening absorbers, rather they diffuse the sound and disrupt standing waves. They are flat, hang from the wall like a painting, and can be covered in fabric available in many colors. You don't have to hire the acoustician to do this yourself, and it's less expensive treating your room than it would be to replace the amp. Please do that first, then decide if you need a new amp.

Give BAT 75SE a try. It's not tubey, euphonic, nor romantic, but it does sound more musical and purer than ARC VT-100 III which I owned for a very brief period and quickly sold after comparing to my BAT 75SE. Could be a good match to your BAT 31

Drastic - Thanks for your comments about the room, but as I tried to indicate previously, further work on room acoustics is not possible, for domestic reasons. Further, as noted, I've already treated the windows, the floors are covered with rugs, there is a fair bit of sound-absorbing furniture in the room, and oil paintins on the walls. The room is not ideal, but equipment I've heard in showrooms does not sound substantially different than in the room. I think the real issue is this: My ideal for hi-fi sound I'd like to listen to is mid-hall Carnegie Hall, and most equipment does not lean in that direction (and the same is often enough true for recordings). And, indeed, you're quite right, I AM trying to use not only the amp, but every piece of equipment I own, as a tone control, in the broadest sense (encompassing timbre, top end, bottom end, etc.). From time to time, I see comments that suggest that there is something wrong with that, and I just don't get it. It's as if there is one only one absolutely correct and ideal system sound, and if my system deviates from that, then I'm doing something wrong. I don't buy into that for a variety of reasons, but that's another thread.

Semi - Thanks very much for letting me know about the BAT vs. the ARC. I'm glad to hear of someone who's heard both. I've wondered if I might like the BAT 75 non-SE better than the BAT 75SE? I understand the SE extends the treble, etc., and am fearful that I may find that less to my liking.

Lissnr - Thank you for your comments about VTL - but I'm puzzled. As noted, I'm now listening to the VTL ST150 (which I think is 6550's) in triode mode. It's really very good in triode mode, I must agree. However, if I'm finding that to nevertheless seem a bit on the bright side, wouldn't I likely feel the same way about VTL's EL34-based gear? That assumes there is a "house" sound for VTL, but maybe the EL34-based gear sounds a bit different?

I'm in the process of looking into older CJ's, by the way. It's been on my list as a possibility for a year or so--now might be the time.

Many thanks to all, and I'm looking forward to any further suggestions.

i was told by a tube seller that the el34 tube is not kind to the ear. i realize that it depends upon the circuit, but my experience listening to many amps using that tube is not very positive. i prefer the sound of an el84 tube. unfortunately many are required to achieve more than 100 watts/channel.

i am considering a beard amp. it is up for sale on audiogon, 70 watts using 24 el84s, ouch !.

the other amp which has been suggested , the mv125 is also on my list.