I'm a little confused about pre-amps right now. I see outboard preamps like the aguilar DB 924, rackmounted ones, with and without effects, onboard ones, and ones built into an amp. The pre-amp built into my SWR just has a gain control and aural enhancer. I see these other ones that seem to have a million different things on them, and I don't know what the hell they do. I know basiclly what a preamp does, but I want to know what a seperate preamp can do for me. Is it just a matter of more tonal control, and maybe some effects? Can they really make a setup sound so much better? explain.