If you have microphonic problems with all the tubes you've used, then you've gotten microphonic tubes pawned off on you by some of the greedy and dishonest tube dealers of whom there are enough. I have the inexpensive Russian NOS which Rogue used to provide - no microphonics. I have RCA's & Sylvania which have none or very low microphonics. I can touch any of the buttons or the case on my unit and not hear microphonic reactions.
Regarding the volume control, I owned two Rogue 99's, and neither had the problem you describe to such a magnitude. When I make small to moderate volume changes at higher volumes, I hardly hear the motor noise at all. It is only at low volume levels that there is a slight motor noise heard through the speakers, but, again, I don't find it unacceptable, and I'm pretty fussy.
It is recommended that the preamp and power amp be plugged into the same outlet. I had some ground loop hum with tube amps connected, but with solid state, it doesn't matter where I used two different outlets or not.
No, the noise floor is not as low as some units, but I believe this has to do with the simplicity of the circuit, and this simplicity of "Keep-it-simple-stupid" may allow the preamp to sound more musical and less processed and damped down sounding. That's what my ears tell me.
