Well, this has to do with my old man's amp. He's just starting up with a new band after being on hiatus. He has an old Sunn Beta combo. (Still in awesome condition considering it's older than I am) But when you play it with the Drive set at 12 'o Clock it distorts a little bit. It really doesn't sound like it's clipping. (Though I'm not 100% sure) The best way I could describe the sound is, it sort of has that clicking sound you get when you touch your strings onto the magnets of your pickup. It almost sounds like something's loose in the amp. (He pulled the grill off and tightened the speaker, but that didn't do anything) He never played it in any real loud bands, (The Bassman 10 he had before was a different story though ) so I don't think he would have damaged the head or speaker by clipping. Any advice is appreciated.