best 50 watt tube amplifier?

It really depends on your speakers and what type of music you listen to. But without any caveats, CJ MV 60, Lumly GL 50 and EAR 534. Preamp with make a difference also.

Don't forget about the WAVAC HE-833 SET monos. Not inexpensive, but certainly a contender for the best at any price. Just my .02

after using a sound level meter I am only using about 32 watts into my 91 decibel efficient Dunlavy 4 speakers to achieve 106 dbc levels, plenty loud. thanks for pointing out the question is the "best" 50 watt tube amplifier available?

Solid state- Accuphase A-50v can't believe the haven't been mentioned yet

Tube-if we are allowing 75watters in this group I third or fourth the Tenor 75Wp and 75Wi. BAT's are worth mentioning as are Atma-sphere's.

This of course depends on what speakers you are using.

Mejames, as the Dunlavy's are not very OTL friendly, you will either need a "big" OTL, such as the Atmasphere MA2s or maybe the MA1s.....or....the Lamm ML1s. a friend tried the Tenors with the Dunlavys and was not satisfied with the dynamics (she switched to Coincident speakers since she loves the Tenors).

my first choice for your speakers and listening priorities would be the 90 watt Lamm ML1s. the Atmaspheres will work but i think the Lamm would be better.