Best 5.1 Stereo Receiver How Do I Install A Stereo Preamp To A 5.1 A/v Receiver?

How do I install a stereo preamp to a 5.1 a/v receiver? - best 5.1 stereo receiver

Right now my PS3 is running uses the digital output and let my HD runs over coax both are connected to the receiver. In the attempt to add a stereo preamp, but it seems that digital connections cancel, I can do anything to get a signal. Am I doing something wrong or unusable digital connections to my RCA connectors?