Well, I am going to re-tube the the power amps I have 20/20 and a 2:90 tubed with with 7581-A's, military NOS 6L6's. Timbe Wolf says to use a 12BZ7 in the first driver spots and matched triodes in the PI spots. I'm glad I found this out from him and I am going to get these soon. As for the MODE...