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You do realize this entire thread is kind of stupid right? Swapping 7 different tubes is a complete waste of time and resources. Get a volt meter, figure out the operating conditions of the tube in the vali. Figure out the plate voltage, and the supply voltage. Then figure out how the tube is being biased and what the bias voltage is.
Once you have these parameters, start looking at tube data sheets and figure out what tube is the most linear and well loaded at those parameters.
For instance if the tube is biased at lowish current and low bias voltage, I would run away from the ECC88 and 6922 type tubes. The 6bq7a is a better tube at lower operating conditions.
However if schiit biased the tube for a bit more current (something in the 15ma range), then the 6922 COULD be better because of its lower plate resistance.
The other catch is to understand that as any of these tubes approach the 0v grid line, all of these tubes start to fall apart. A tube with a higher amplification factor could help you crank the volume up higher whilst staying away from the 0v gird line and keeping distortion at a minimum.
Blindly swapping tubes around without understanding the circuit is just throwing good money after bad.