Range Rover 2001 P38 Sound problem

Hi I am ready for throwing the Towel in, had a problem with my sound system everything just went silent. radio CD sat nav etc. tried various fuses checked wiring etc etc., put it down to my DSP amp having a fault, last week i managed to source one from E bay plugged it on and yeah you guessed it nothing but a faint crackle from the Sub Woofer box, I have checked all of the 10 speakers and all work fine except for a Bass speaker in the right front door, tried again with it disconnected but made no difference. if any one can shed any light on this problem then I would be most grateful.