I recently bought a Vox AC30cc (December 15th) and have been really enjoying it. However, in the last few days it does not sound like it did before. When playing it sounds like someone turns the bass up all the way and then it returns to where it is set at, every few minutes. The amp has also got a rattle on certain notes, namely A or F#. I already replaced the stock tubes right after the holidays and thought maybe one of them were bad, but the stock tubes do the same thing. Do I give up on it and get a different one; I have a few days to return left? Give up on the custom classics and find something else? I already have $200+ in tubes, so its hard to decide.