Can someone please explain to me what a pre amp is for. Does it have any role in a home theatre setup. especially when you have a nice A/V reciever. Sorry if this has been gone over already.
an A/V pre-amp would be used when amplification is provided by a "separate" power amp(s).
receivers perform the functions that both the pre-amp and amp(s) perform in a "separates" setup. so no, you don't need a pre-amp if you already have an A/V receiver.
In Home Theatre, also sometimes refered to as pre/pro, where the pre is the preamp (which has the inputs/outputs, switches between the sources, etc) and pro is the signal processor section which does any of the conversion/decoding, for example Dolby Digital, dts, etc etc. The outputs go to the external amplifier(s) as has been posted above.