Hey Folks - been awhile.  I built my OTS last Feb/March and had it working beautifully within a week or so - only issues were a missed ground and swapping the OT primaries -- nasty oscillations there man. 

I want to try a pair of these Valve Art KT66s in my OTS.  These are real nice sounding, big-bottle (replicas actually) tubes - they work real nice in my JTM45/Bluesbreaker...  Anyway - I think I know my stuff (built 7 amps now, incl. reverbs, buffered loops, 4 el34, etc varieties) well enough to do this and check that it is ok.  The main issue is a typical KT66 wants 1500 ma on the heaters (varies twixt brands), while the 6L6 uses closer to 900 ma current.  I THINK the OTS' power tranny has plenty current to spare (nik - is the same pt for the 100 watt OTS?  If so, I have my answer).  Simple matter of installing them and checking the heater voltage to see if it drops any/much, I believe.  Thinking that an inadequate heater supply would end up delivering 6 volts or less if overloaded - yes?   As far as bias --- 60 to 70% of max. for nice BIG clean - closer to 75% max diss. for BIG dirty (think bluesbreaker I think)...  bias not a big problem -- ensuring the extra heater current required is available is the main issue in sub'ing KT66 for 6L6.  What say ye fellow builders and tinkerers?

Cheers and thanks, Stephen