Some Marantz 8B enthusiasts recommend using KT66 and not EL34 for the
best sound using the same EL34 bias. I have tried to put some Chinese
KT66 on my 8b. Even setting the bias at minimum level, the pointer of
8b bias meter is still moved beyond the bias mark (about 1/3 between
the bias mark and the dot). The sound however is creamy and smooth and
all 4 KT66 are looked fine (tubes did not glow red).
My questions a-

1) whether it is safe to use KT66 on M8b but how to set the bias
properly using the 8b's meter.

2) whether using KT66 would damage the 8b in long run (i.e. would KT66
put extra strain to my 8b?).

Please advise and thanks.