That, my man, would depend on what you are recording onto. The general rule of thumb is as high as you can go without any component in the signal chain being overloaded and clipping. In a digital domain, the highest peaks want to be about -4db, and if you are recording to tape, +4 db may be OK. Lots of people will give you different numbers, but I would say turn it up until you hear that nasssty crack. That's clipping. Then turn it down until you don't. Then turn it down a little bit more, to give yourself some headroom, which is like your safety margin.-Richie