Short version, if you dont like to read a lot: I bought a Carvin MB10, used it without problem for weekly rehearsals and occasional gigs for about 6 months. One day, I flipped the mute switch to change basses, flipped it again, and the amp popped. Thereafter, there was a distortion, especially on the low notes, at all volumes, and even through headphones with the amp speakers turned all the way down. This distortion occurs no matter what bass I use with the amp. More details, if you care: I sent it to Carvin. They kept it for two months, sent it back, never specified the problem, but simply said replaced the amp module, tested all functions. I assume this means they replaced the whole pre-amp/amp section, leaving the original speakers and cabinet? (The control section even has a new serial number on it, which makes me think thats exactly what they did). However, it is still doing it. I even bought another MB10 and have A/Bd them the new one works fine, the older one distorts. Before I thought to try it through the headphones (Im slow sometimes ), I even bought a new 10 speaker and replaced it still distorts. That, and the fact that it happens through the headphones (which I should have tried first ah well, I have a backup speaker if I ever blow one ) indicates to me that it isnt the main speaker. Im going to take it somewhere local when I get a chance, but in the meantime, Id be curious if anyone has any ideas. Thanks in advance.