So I practiced today on my SVT3PRO with no problem..then I had a gig tonight so I get everything set up and get everything plugged in and no sound. So I ran my out cable to another cabinet and still nothing (making sure it wasn't my cabinet)....I took the top off and all of the tubes look ok....I changed the fuse on the back (although it was a 2 amp fuse instead of a 10 amp) and still nothing. The only thing coming out was a crackling noise...but only when I hit my A string. So I hooked up a Fender Bassman 50 amp(my buddies) the cabinet worked fine as did my bass...so I know it is my amp. Any ideas?? I have no idea what it might be...I looked at the entire inside and didn't see anything that look fried or anything.