4 Channel Cutout

[S4LVA]

Hey, I'm having a problem with my 4 channel amp connected to my speakers. They have been running fine since they were installed around 4 years ago and now its starting to cut out after about 2 minutes of music.

I have another monoblock amp connected and running another set of rca cables from the 4 channel to the sub also and the bass still plays but the speakers dont.

Does anyone have any idea what could be wrong with the amp? Its just a cheap audioline amp but its done its job and lasted years, could be replaced for another one but its just the rewiring and disconecting that's stopping me from changing it before diagnosing the problem. Amps mounted next to the battery behind the sway bar or whatever its called in the boot.