Well, if the input is 10.5v to the opus, then it shuts down. The load removed, voltage goes up to 11.33, and (since "ignition" is still on) the opus restarts.
You should probably measure the amps going into the opus just to be safe. I had a similar problem where a bench supply I was using was supposed to give 11A on 12V, but as soon as I had even 3A on it, the rail drops to about 10v. Just try a different power supply.