I may have isolated the cause, but leads me to another problem I guess. It seems that if the line voltage drops too low, it stops output. Somewhere around 11.85V. As I raise volume, line voltage at the amp lowers.
What is odd though is that PSUmoni shows line 1 at 12.1V, my meter reads 11.75 at the amp. I trust my meter much more. I have the setup powered through the P2140.