I am about to take possession of a new amp. It uses 4× KT90, 4×6922 and 2×6H30. I understand the amp. is self biasing. In the case of valve failure, is it OK to replace individual valves? Is it better to replace pairs? Please not quads! At this point I am only concerned in keeping the amp. on the road, not exploring alternative valve sets. All advice gratefully received.
BrianS
BrianS