I've never had the chance to play one, but I'm thinking about buying a mid 70s DR online. I don't love the idea of buying without trying, but I don't exactly see vintage deluxe reverbs all over the place...at least close to me, anyway... There's what looks to be a nice, mostly original mid 70s deluxe reverb, at a decent price. The person listing it mentions a "very mild hum" and states that it's normal for vintage amps to have some mild humming. Tell me, wiser-than-me gear hounds, does this sound about right? Or should I be wary? Thanks!