Just talked to Pete at HSU. The problem does indeed look like the amp.(tyvm John)
On a side note. I AM SO IMPRESSED with HSU customer service.
Pete gave me detailed instructions on everything I need to do to get this sub back to life and did it all very pleasantly at that.
Kinda reminds me of the times I've talked to Axiom customer service.

LIFE IS SHORT.
DON'T BE A DICK.