To contradict some of the opinions here, I was in a similar position and decided to replace the amplifier portion of my receiver with an Outlaw 7500. It was a simple and seamless upgrade. HOWEVER, my ears could not tell the difference with the soundtracks I listened to.
Although many say that you can achieve greater soundstage and the headroom will undoubtedly give better response, in my application, the difference with my RF-7's was negligible using my unscientific measurement methods.
In retrospect, the money spent only helped satisfy my upgrade needs. Time might have been better spent determining frequency response of the room and doing the appropriate treatments. (Too bad I don't have the tools nor the expertise in this area)