Audio input grounding issues with the Power Mac 7500 and 8500 models can sometimes introduce hum in your recorded audio signal when recording into Deck or Peak using the RCA inputs. Apple recommends using the stereo mini jack input for the best audio quality when recording into these models for numerous reasons, one of which is that there is no potential for hum when using the minijack input. If you must use the RCA jacks for input, you should be sure to plug the computer's AC plug into the same power outlet as the rest of your audio equipment to decrease the potential for hum associated with a ground loop.