I have a pioneer premier deh-5500mp. I'm not sure on the pre-out voltage i lost the manual and I can't find it on Pioneer's site or on the web. I have an Orion HCCA 250 Digital Reference amp that i'm running at 1ohm. I've been told to turn the volume up 3/4 of the way and set the gain until there is no distortion, but I don't know how accurate this method is. thanks for any help you can provide.