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Psvane tubes

1. Treasure KT88-Z CB Cobalt Blue Bottle Super Tube (GF-Select, Quad) | Psvane & Treasure Audio Tubes

I guess these are the tubes in question ^^^^

Given the constraints of the question, I would probably pick manual bias with the understanding that the cathode resistor value might have to be adjusted. The safe play is auto bias, but it sounds like those are weaker tubes.

At $500 Canadian / tubes, I accept zero financial responsibility for any and all consequences of this answer. All risk of loss is on the end user of the proferred information; zero, zip, nada, none on me.

I would probably just get some blue glass JJ's. Or red glass JJ's, but you usually have to get the red glass tubes direct from the factory outlet - last time I did that they socked me with VAT.