Legacy LA1478 Car Amp "causes sound fade down speaker" Questions

...sound comes out everythings hooked up right and lights come on. the only way you can get a little bit of sund of it by hooken the speaker wires up to both posative on the amp theres a chance you may ...

...sound via stereo(Sony xplode stereo too) by the low and sub levels and the amp slowly faded out on a long base hit(using the song voodoo by godsmack to tune) after that the protect light stayed green ...