There is a reason why we always see the same tubes used over and over and over and... , designers usually don't like to venture outside of the beaten path.

The output sits between two transformers. The input (interstage?) drives the tube and the tube drives the output transformer. The designer, Cristoff, is a nice guy and does his best to answer questions. The first buyer - whose thread you can over on brand x - seems to be having €8000 (or was it 6?) buddhist-like audio orgasms over this amp. He's taking it to a messe (that's like a jam) in Finland, if you have the yen to go.