This is from a well respected 30 year ARC dealer owner:
With matched tubes, all of which are well within the bias range of a Ref 110, it is no problem. Issues arise when people purchase 8 random tubes and “plug and play.”
KT150s in Audio Research Ref 110.
Is anyone using KT150s in the Ref 110 and what is your opinion please? ARC told me that they weren't recommended but I've read differently. I'm currently using KT120s.