Yeah..you are quite right, I'll save the 6550's for the Sunn.
No Fetron on this one. It has 5881's in it now,
but I don't know if it was biased properly by the previous owner.
I have a new set of Mesa 6L6 STR's rated at 10, so I guess they are on the hot side.
I have three old westinghouse 6L6 GC's (what happened to the fourth??).
Might be time to learn to bias my own amps , ...[self-biasing?]. ; )
I pulled out the old G-100 celestion and have an Altec ready to install...I might try a D131 too,
they are getting to be a favorite of mine.
The amp as it was , had a harsh upper end that I'm hoping to smooth out ( I'll try some different pre tubes too), and getting to know the amp better in the process is a plus.
thanks for the sound advice !