The Mid Mono has had three revisions and the early ones can not use the big KT tubes. Mike told me not even to use KT 90 on my second rev Mid Monos.
I would contact him. He is a straight shooter.
Quicksilver V4 tubes
My monoblocks are from 2006 and I'm looking to retube them I've had the KT 88s in them and now I'm running EL34's but would like to go back to a more powerful tube such as maybe the KT150 would like some suggestions