[Screws]

Tubes are tubes. There's no such thing as compressor tubes, only tubes used in a compression circuit. A "Vari-Mu" comp actually does the compression in the tubes, but the Avalon isn't a vari-mu design.

According to the manual there are three tubes that take the place of three class A amplifiers in the circuit when TSP is switched in. The tube path sounds bigger with a round bottom and sweeter, more sparkly top.

The schematic seems to show (I'm not real hot at reading schematics) one tube is post compressor as a buffer amp and one is for each side as an output line amp.

The compressor itself is an opto type, and the eq is a discrete, class A passive type.