Quite a few years ago I too dipped my toe into the tube market. Cheap Chinese one I modified, An old HK A12 I restored, Built a "red light". Nothing I could afford was any good even considering the 6 to 12W range. Then I heard the Cary monoblocks on some Epos speakers. 35W if I remember. It was like melted butter all over the music. Soft, comfortable, could listen all day for my kind of music. Not for heavy metal or electronic techno stuff. Folk, Jazz, classical guitar etc. Alas, out of my reach. As was Audio Research, Mac and some vintage Lux I found even though I very much liked their version of distortion. Hard to remember, but I think I heard a Vincent hybrid too. I grew up with tubes of course as that is what we had. My first amp was a 30W Knight. It was not SOA and by the time I could afford a stereo, A Sanyo, yes SANYO Plus 55 was out there and hooked me on MOSFETs.
Yea, distortion. If you measure these amps, you will find it is not simple even vs odd and depending on topology, I can mimic that in a SS input stage*. It is something else I do not think we understand how to measure or if we are measuring it, we are not interpreting the measurements the way our brains are.
I do not understand why, but tube amps seem to be more powerful than a SS with the same power rating. Where a 20W SS may be marginal, tubes seem to carry it off better. By the time you get to 50W, seems they are not lacking. Rock solid bass is not their strong point, but with a sub, that is totally a non-issue.
Anyway, instead I built my MOSFET amp I still use today though for some irrational reason I am looking for a newer one. I understand the tube side, just not going there as amps good enough are still out of my range. Then you have the age-old arguments about KT88, EL34, B300's.
I am also temped to slip in a tube line stage, Schiit Sega + maybe. Basically, a distortion generator, but a very nice distortion generator. The other side of me is focused on DACs. Probably R2R or Qutest. My 99% focus is on vocal sibilance, "metallic" tinge to a classical guitar bass strings, horn sharpness etc. These are things I can clearly hear even in a store. I want to listen all day, no fatigue which seems to be mostly DAC centric. Others are focused on impact, imaging, air etc. DACs have improved immensely in the last couple of years. The best of the best two years ago may be mid-pack today. Talking sound, not spec chasing.
Might listen to a Hegel MOSFET before you commit to tubes. A lot of the "musicality" if you pardon the arm chair reviewer vague terminology without the heat and ageing problems. Not as much "tubieness" as a Cary, but not far from a VTL if my memory is correct. If I win the lottery, I think I would give tubes a try again. If you find an old Silver Seven, give it a listen.
Hope that adds helpfully to the above members experiences.
* Have some fun. Play with input LTP current matching of a bi-polar vs a FET input.
PS. yea, the old MK 3's had good transformers. Toss in modern caps, clean up the heater power and they might still be competitive. Then play with the grid resister values to tune to taste. (See VTL documentation) Old CJ MV50 was similar.
