Grant,
the volume setting on your IPOD is the sensitivity input on the AUX of the Headunit.
This means you can control the volume of the system with jsut the IPOD if everything is set right!
I had this same issue over the weekend...to bad for me it blew 4 or my 6 tower speakers...but I finally have everything dialed in correctly now!
My comments on the RCA volt levels, yes they do produce nearly what the book says the unit does, but this is a variable ratio based on the volume setting. The highest volume of the unit should produce the greatest voltage. ALWAYS step-down the volume a few clicks and THEN adjust the gains on the EQ's then the amps. The Amps gains as a rule of thumb should only be set up to HALF the actual amount you can set them...after that your artificially trying to get more volume out of it than it is capable of.
Audio Control has a great "white-paper" on level adjusting and settings that is a great guide for other non-AC units as well. Check the website
www.audiocontrol.com KG