A bass player / singer friend of mine has a Hartke HA2000 head and 4.5xl cabinet. Bought them used. He plays the rig at a gig and says it sounds bad. Gives me the cabinet to diagnose / repair, and I find a 10" driver that has a serious issue with the surround coming unglued from the frame. You could literally stick your finger between the surround and frame in several places. So I re-glue (as per recommendation of Orange County Speaker) and seems all is well. The driver sounded fine and was submitted to a frequency sweep on a test tone generator. Passed the test (as did the remaining 3 10's from that cabinet). He plays the rig live again, and his amp / cab combination still sound bad. So, he gives me the head and cabinet to diagnose. I find that the tube preamp sounds horrid when I play at the same gain levels he is using live. So, I replaced the preamp tube, work the tube gain control a few times, and it solved the problem. The head sounded fine. I was unable to coax the head and cabinet to misbehave. He takes the head / cab to his next gig, it still has some kind of distorted / bad sounding problem. Keep in mind, he is a pick player with a heavy hit, and is playing this rig (a 120 watt head and the 4.5xl cabinet) rather loud. I'm beginning to wonder if he is just clipping the hell out of the head, and our attempts to fix are futile.