I really enjoy this forum and how the experts share their rare knowledge of these vintage amps. I see that some have posted that for amps that have sat un-powered for years, it can damage them if you power them up, and that it is advisable to have a competent tech do it. Many of these high powered amps are too loud so they sit unused. How long is "too long" for a vintage tube amp to sit unused, as far as damage is concerned? Does an amp need to be plugged into a speaker cab when it is powered up even if you're not going to play an instrument through it? How often should a tube amp be powered up to keep it healthy? As a side issue, for amps that are "too loud" for home use, is one possible solution (instead of a MV) to plug it into a Variac and just dial down the voltage so you can push the amp without going deaf?