Virtually every large car amp uses the IR21844 IC. IF you need real power abouve about 2KW, you don't have many options.
These amps are decent but can be difficult to make reliable after they fail, generally due to intermittent problems and that's mostly intermittent shorts in the inductors.
If you think this is sneaky, you haven't seen the ICs that are marked with legitimate part numbers that are for a different IC. The marking look 100% legit, not a re-mark like NTE or other IC markings where they black the original marks out and re-print. They even mix up the IC manufacturer for markings. They include original logos and date codes. They do it on ICs and other smaller semis. It's pointless, for the most part.