I am the original owner of two Carver M-2120 car amps which I ran in my 1991 two door Ford Explorer.
I took advantage of the built in crossover via the following set up:
Amp one was used with four JBL Grand Touring 5203 speakers (mid range and tweaters).
Amp two was used with a MTX 10" subwoofer box which sat in the cargo area of the vehicle.
I loved the amps enough that I removed them when I sold the vehicle in 2001 and still have them sitting in my house...wondering what to do with them since I am not aware of anyone who restores car amps?
The amps have plenty of power and sounded nice, although, maybe a little loud in the background noise department...maybe that could be resolved with some upgraded electronic components?