I bought a new sub boss phantom?

Sounds like you went from a Kicker Comp to a Boss P156dvc.

The Kicker is a single voice coil sub, and 250w rms.

The boss is a dual voice coil sub and "claims" to be 1500w rms. Unfortunately, Boss has a long standing tradition of lying about the power capability of their equipment. If you put a REAL 1500w amp on that sub you'd make a paper weight out of it in a few minutes, if not seconds.

Realistically, I doubt it is capable of handling more than 400 or 500w rms. That's 200-250w rms per voice coil.

Since you seem to be hung up on peak power ratings I have to assume your "1500w" amp isn't really 1500w. However, even if it's 400 or 500 or 600w rms and you only connected it to one of the Boss subs' ~250w voice coils it wouldn't be a surprise if they're suffering from too much power/heat.

I've 4 of those audio system in my stay away from Durango in an enclosed box and i vigour them with 2 Pyle 4000W 4 Channel amps. You could bridge these amps for 2000W X 2 they usually dont price that much. Round $one hundred ten. Mine sounds real loud however for you with only one Phantom there are many options to decide upon from, just will depend on your cost range. But look for one that's around 1000W X 1, a mono amp that's 2 ohm stable.