I have a Integra receiver that sounds very good but after hearing so much praise for the 750 i am thinking on geting one. Do you think that the pairing with the Integra 7.1 and the 750 will improve my system since the 7.1 is not a pre-amp?

Forgot to add that my speakers are Klipsch Reference all around

It should help and will definitely be noticible. Everything that you now hear in the Integra over what you previously had (I'm assuming that you moved up from the $500-600 crowd). I suggest this form of upgrade over replacing and buying a flagship AVR as the processing is quite similar but the amplification is much better overall (I'd advise putting the amp on a different circuit as well).