Just got my first tube (hybrid) amp, a brand new, used Ampeg SVT-6 Pro. It's obviously seen quite a few gigs, but for $350, I couldn't go wrong. As far as I know, it's working properly. I've got it opened up and I've checked all of the tubes for continuity. My last concern is the bias. I'm just wondering if I should attempt to check or adjust it. I've looked for more information online but can't seem to find much. It only has one bias adjustment and it doesn't have a bias tester spot like a lot of tube amps have. if I could take it to somebody and have it fully cleaned up and checked out I would, But I don't have the money. Any help would be greatly appreciated.