Sounds like some type of grounding problem to me...Ir would be interesting to see what would happen if you lifted the ground...Just a thought
tubed preamp off and ss amp left on?
Why can't I leave my my ss amp turned on with the tubed preamp turned off? Loud hum occurs through speakers with this condition. When I had a ss preamp I could leave the amp powered all the time with the pre off. I would leave all powered up but concerned about the preamp tubes wearing prematurely. Is it a reasonable conclusion that I could leave everything powered on all the time and just change the tubes once per year?