I tried it again when I got home (I found another patch cable in my box-o-wires), and discovered that there is an audio out level adjustment on the Roady (it is only present when something is hooked up to the line output). It wasn't a huge boost, but it helped.

I ordered a ground loop isolator from Crutchfield and will report on what I find out. I am hoping this will clear up the noise, and that the boost in the audio out level will help with the volume problems.

More to come...