My Invader recently blew a tube. I played, there came a loud pop, then a lot of fizzling and crackling before the volume disappeared completely. I promptly turned it off . I was afraid that the amp would have been damaged somehow and that even a fresh tube swap wouldn't get the old tone back. The reason for this is my friend experienced this exact thing not too long ago. His amp blew a tube, and he had a tech install a set of fresh new tubes of the same brand. Biased correctly and everything was supposed to be good to go. Except it wasn't... His old tone was gone and the tone he had now was much more trebly and fizzy. Not a huge difference in tone (it wasn't fubar), but definitely not the same. He got yet another identical set of tubes installed, but yet again the tone was crappy. So back to my story. I got my invader back from my tech (who is really good, btw). I had him install a set of =C= power tubes, so they are a little bit different than the stock tubes (which are Sovtek), so I expect a minute difference in tone. Now, the tone is okay and not too different (I attribute the little difference there is to the new tubes), but there are now "ghost notes" or undernotes to the notes I play. They stick out most on the D and G string above the 12'th fret, but they are audible everywhere. A ghost note is basically a tone that follows what you play in what sounds like about an octave below (though not the same key). It's very quiet, so I didn't notice it at first when I switched on the amp. It's definitely there, though, and now that I know it's there it's all I can hear when I play. My ears get fixated towards it. Imagine it as a slight humming sound, folowing the keys you play at any given moment in a note somewhere below. It's only audible when playing single notes on one string... ----- So if you've stuck with me through that wall of text, you deserve a cookie. Now here comes the question: What the hell is wrong now? I've done some googling, and it appears that most people confuse ghost notes with "cone cry" from the speakers. This is not that, as I play through the same cabinet as before. A ghost note isn't erratic and mechanical sounding like that, it's basically a hum that is created within the amp. I read that it is often a sign of bad caps. Could a cap have gotten bad from the power tubes going? Something is not right, and I am getting damn tired of tube amps right about now. 2 years of Mesa problems, and after two months this Invader has been at a tech twice because of bullshit. I just want to get back to playing and enjoying guitar, and not worry about whether or not my gear sounds right. So before I take it down to my tech for the third time, are there anyone here who have any ideas?