Tube Rolling questions from a recent addict:

I recently entered the wonderful world of vacuum tubes with a Cary SLI-80 integrated amp. WOW what a sound this thing produces! The Cary and its seductive little glowing crystals of joy has made the single most dramatic improvement to the sound of my system since I added my Infinity IRS Delta speakers. Now I understand why tube-heads go on about mysterious NOS finds and seemingly magical differences between certain tubes. I’m both happy, and sad, to say that I’m hooked!

Anyway, on to my questions: 

• When tube rolling, what are some recommended strategies when comparing the sound quality of different tubes?

• Is it OK to power your amp/preamp down, switch tubes, and then power right back on a couple minutes later? I know tubes don’t like to be power cycled like that. But how else can one compare the sound of different tubes?

• Generally, is there a bigger sonic difference between rolling preamp tubes, or power output tubes? (I know, I know, YMMV.)

• And my most technical question. The Cary SLI-80 uses a one 6SN7 tube per channel as a “phase inverter”. From the manual, “the phase inverter is a self-balancing split load configuration utilizing the 6SN7”. Is this “phase inverter” part of the audio signal path? Can I expect to hear differences in rolling different tubes in that spot?

Thanks in advance for any other Tube Rolling 101 advice!

(P.S. – Thanks to everyone on Audiogon that makes it, IMO, one of the best places anywhere for higher-end audio and music fans everywhere.)