@thieliste No, I have not compared any other power tubes in the amp. I am quite happy with the KT150’s. In order to utilize other power tubes besides KT150’s the amp needs to go through an internal modification to accept those tubes. I have rolled in various driver tubes, as the amp is highly sensitive in that area, At the moment i am using a mix of RCA Clear tops and NOS Tungsol’s in those locations.
I do know that a friend of mine believes that in his amp, the KT120’s sound better than the KT150’s, but this is a different circuit and I think the Mk2 Jadis amps are designed for the KT150’s.