Hi James:
I also have similar situation with 7BSST2s where I would get a big POP noise when I first turn on the amps. I have narrowed the situation to where when I have my Manley Reference Tube Preamp turn on first and then if I were to turn on the 7BSST2s within 5 to 10 seconds, I am sure to get the POP that is loud enough for me to worry that I may damage the Maggie 20.1s. However, when I turn on the preamp first and wait about >30 seconds and then turn on the 7BSST2s, I get almost no turn on noise.
Thus the source of the problem points to the Manley preamp. On the other hand, I understood the 7BSST2s to have soft-start circuit (or is it a delay on output circuit?) to prevent such a POP at power up...
Are the 7BSSTs working properly if I am having issues at power up?
Thanks,
ki