Well, I took the time to go through and disconnect all the connections from the amp, and then slowly started reconnecting things double checking everything as I went. No change.
But then a little positive progress. I read through the Sony article that
@JMT posted (Thanks Dude!), and one thing caught my eye. It said to set the volume to normal listening level with the music on pause, and
if you hear static reduce the gain and increase the volume until you and find a balance between the two.
So I adjusted the gain knob (increased it, according to the markings) and sure enough the static was markedly reduced. Now in the documentation on the amp it said to set the gain to the voltage output on the head unit - 4 volts in my case. The documentation was clear: Do not set the gain by ear - set it to the proper voltage, which is what I had done.
The 3 gain adjustment dials are marked with voltage from 12 - .5 volts, clockwise, so I had originally set it at where 4 volts should have been according to the markings. I played with the gain a bit and found a setting which balanced the static and the volume. Funny, it wound up about where the 8 volt mark would be according to the markings - or at about where the 4 volt mark would be if the markings were reversed - which I'm thinking they are...
Still a little static, but a hell of a lot better than it was. I'll play with it a bit more tomorrow.