I know this scenario isn't ideal but if you are in the position where you need to use the amp section of a receiver to power a Pre/Pro here are some instructions. I was forced into an early upgrade so am doing this now. I was given some ideas but I couldn't find any explicit instructions anywhere so maybe these will help someone in the future.
1. Do a factory reset on the receiver
2. Connect DVD/BRD player to receiver
3. Use a setup disc that has test tones, I used my old Digital Video Essentials DVD
4. Play the test tones from the set up disc and measure output with an SPL meter
5. Turn the volume up on the receiver until the output = 75db
6. Make note of the volume setting of the receiver; always set the volume of the receiver to that setting and never change it
7. Use the multi-channel input on the receiver and any direct or pure audio mode so there is no additional processing done in the receiver