After playing through my amp for two minutes or so at reasonable volumes, not loud enough to annoy my wife, I have a sudden drop in volume. The tone doesn't change, I just lose volume. Nothing smokes, nothing feels like it's over heating, nothing is visually wrong. I've tried different cables and different plugs in my house. The amp is a valveking 212. I've considered a blown speaker, but I've heard those before and this doesn't sound like that to me. Suggestions other than acquiring a new amp? Thanks!
Hebrews 12: 29 "For our God is a consuming fire."

Warmoth humbucker-tele (specs soon to change), EHX 44 magnum power amp into 1x12 with WGS Retro 30 and a Barber Electronics Dual Unlimited.
Big drops in volume like that are usually indicative of worn power valves. Get some some new tubes dude. I recommend JJ 6L6. Order a matched quad.

Hit up the Only Valveking thread if you need more assistance of if that end up not being the problem.