Long story short, we play at a number of venues (mostly bars, old buildings with poor maintenance) that I believe have crappy power. I can hear it sometimes, amps do weird stuff, and also think it was probably the cause for my tube amp bias power supply, failing during a gig. Based on that, is there any reason to use a variable output transformer coming from the "mains"? Long version: It's a 300 watt Eden E300T, about eleven years old. It would sound "funny" at some places, some distortion and reduced volume, line noise. After the gig that broke it, I checked the bias current (actually voltage across resistors) and it would drift from below normal to zero over a few seconds after power up. (Normal voltage drop across a resistor for each tube is proportional to current in this case.) I'm pretty sure I'll have to get the power supply board repaired. And I really really like this amp, even though I'm using one of the newer, more "powerful" non-tube amps right now. I miss my tone!!! And grunt. Other people have had power issues at the one place in particular, to the point that one band I know has their drummer/electrician run a line to them directly from the breaker box. Lots of fridges, neon signs, fans, etc. for loads, all noisy and potentially low voltage. It's at a campground off of one utility transformer, lots of A/C units running in summer. (And yes, the drummer/electrician thing is kinda scary! lol) Let's face it, if nothing is seriously broke, no bar or older venue owner is going to spend anything on upgrading their wiring. I see that you can pick up a 10 Amp variable transformer for less than a hundred bucks. They look like the pic below. Note that these are NOT auto-transformers, they don't adjust themselves. It would provide noise protection, prevent ground loop issues, really big surges, smooth out the sine waves, and allow me to dial in the right voltage, even at the expense of drawing another amp off of the outlet; I don't care as long as any voltage adjustments are minor, it's only going to add maybe another Ampere max by raising the output 10V. Or is there an alternate solution for "conditioning" crappy power available that doesn't cost a small fortune? Some sort of filter at least? It's nothing that a surge suppressor or "power distribution box" would address. Thanks in advance for any help anyone can provide. Oh, and no, we're not going to stop playing those places, this is the reality of being a cover band that plays 30 gigs a year at maybe 20 different rural-regional venues; it's the only client base we have.