Ive been doing some direct in to the PA stuff from time to time and and was wondering is thier a circuit that is basically a clean amp sound so that I can run drives and other effects in front of it to give me a fatter and more realistic tone?
Thanks guys!

One of the amp 'sims', tuned/biased to clean with a cab-sim following it?

  Fender Deluxe Pedal.
  A digital Pedal.
  An Amp Sim...
  Speaker Simulator, or something similar, perhaps a buffer and a two pole LP filter'd do it. Signal boosting is probably not desirable, as distortion in the console is generally a cameo effect at best.
  Rolling off the high frequencies 'sharply' [with multi-pole filter] will help keep the string from 'blapping' the HF drivers most PA systems utilize and guitar amps don't.

I like the Tonemender and Condor from runoffgroove.

My first thought was "Sansamp", but I think that's more like a versatile overdrive pedal ..  or can you get clean sounds out of it?

I would check out some simple hi-fi preamp (mosfet-based, maybe?) and add a conder cab sim afterwards...
Maybe you could also integrate a DI Box ... always useful to have a DI out and go straight to XLR.

Let me know how it goes... I've also been thinking about building something similar as a backup device to have on my pedalboard.

If you're playing bass, I know that Hartke has a DI pedal that is basically a Hartke preamp section in a stompbox. I haven't heard it but I have owned nothing but Hartke amps and they sound quite clean. Might be able to get away with using it for guitar.

You could use the Duncan Amps tone stack calculator to approximate a speaker response then build it with fixed components? Depends how close you need/want to be.