Hi,
  I bought a used Trace Elliot Supertramp Stereo Twin Chorus a year ago (green tolex) and I'm having an intermittant issue with it. Background, whoever owned it before me cannibalized the Celestion speakers and replaced them with one crap Dean Markley vintage rock and one totally unmarked noname speaker. I plan on replacing these with some Webers. My problem is that a few times per week when I power the amp on it makes loud cracking sounds. Doesn't matter what's plugged in or where the volume is, or which channel I'm on. Usually if I turn the amp off for a few minutes, then pwer back on it fixes the problem, however today it didn't. Today the problem went away after the amp warmed up for a couple minutes. My question is if this nis indicative of a major underlying problem. I don't want to invest in replacement speakers if the amp itself is a bone. When it is working everything sounds just great and I love the amp. Thanks!