Problem found and eliminated. Center channel works fine now.

I decided to start eliminating things to see if there was some other problem. The VP100 works fine by itself, but the M2 by itself would cause the receiver to shut down. When I removed the banana plugs at the M2 and just hardwired it, it started working. There was some pressure applied to the banana plugs by the mounting bracket. This must of caused a short inside the M2.

No need for a monoblock now.