From your description I get the impression that you made no changes to any wiring, it just stopped, right?
Do you get absolutely nothing at all from the subs? No very faint vocals if you listen really close? The amp doesn't go into protection? (if it has such a mode) If so, it could be a short in the speaker wiring... disconnect speaker wires at amp and measure (resistance) between the wires (should be probably around 3.5 Ohm for a nominal 4 Ohm speaker. Also measure between each wire and ground - should be infinite.

What are the filters set to?

Try playing a constant volume test note (50 - 60 Hz) and put a voltmeter on the speaker outputs (AC, >20V or so range and check if you get anything there...150W into 4 Ohm corresponds to roughly 24.5V (lower than max volume of course <-->lower voltages
ANything there would mean the signal reaches the amp and gets amplified - look at the sub wiring (amp to enclosure and also inside the enclosure.

Do you have another amp to test with - to check that you have a signal arriving on the RCA wires? Or atry another signal wource - maybe a portable player and 3.5mm to RCA adapter wire. Either turn on the normal HU/empeg while testing, or turn on the amp manually by bridging the remote turn on terminal to the +12V (B+) terminal if you disconnected the remote along with the RCA wires... You could also use the voltmeter and mesure if you get the signal to the amp input.

You didn't say in exactly what situation you checked the power to the amp:
Iif you have an AGU fuse (glass tube with metal end caps) it can be bad under load while it otherwise checks out - often due to a partially melted connection between one of the metal caps and the actual fuse element, which causes a large voltage drop as you pull a big current through it (simply replacing the fuse is probably the simplest way to safely test it)