I just picked up a rebel 20 sunday and just had some questions. It was new in the box when I got it, and when I set up and fired it up it was making some crackling/popping noises. I played around with it for a while and couldn't get it to go away. I let it sit for day and tried it out again last night with the same result. After let it sit for about an hour it started to get better, and now it seems fairly normal sounding. One thing I noticed when checking out the tubes is that the writing on the EL84 tube to the right almost looks like it was burnt. It's not red it's more of a grey. I didn't know if this was normal or not. I've had issues with GC in the past so I thought I would just see if all this is normal or if I have or had a tube issue at all. The amp sounds amazing and the quality is outstanding. Thanks in advance for any answers.