Is it a 6h33c, or a 6C33b? My Joule Electra monoblocs use the 6c's.
Yes, very big and very, but not extremely, hot tubes. See my avatar -- each monobloc has 6, and is rated at 100 w. per.
You're right to check the bias frequently, at least until you're sure they are stable. One of mine apparently ran away and melted part of the acrylic top plate before I discovered it.
One problem is finding solid tube sockets for the 6c33b that don't let the tubes rock out of place if you jiggle them. This can cause poor socket connections, which might have been my problem. I think I'll contact Almarro (and BAT) to see if they have solved that problem and if I can get replacement sockets. Big job, at 12 for the two amps!
Aside from all that, yes, excellent tubes, great clarity and linearity. Great for OTL duty.
how much do these cost - just by curiosity