460 Mach sound bass cuts out

[Ramrod]

I have a 97 gt conv. with th 460 Mach sound sytem but have aftermarket stereo. Everytime I turn up the volume acouple of seconds later bang no bass. Is it possibly the rear amps? HELP! Please

 

[2BADSTANGS]

Possibly the rear amps,as they supply the lower frequinces to your system. But it would help diagnosis if you have the info on how your aftermarket sterio was interfaced with the mach system.