So i'm trying to troubleshoot a radio issue, have power to radio but no sound.

I have replaced radio with known good,
Checked Fuses in interior panel 2 fuses were fine.
swapped with a known good amplifer from another rover,
swapped rear passenger headphone modules.

Message on radio says "S 1 FOR" which I get find any info in manuals, forums or online.

Also audio works fine when plugging in headphone jacks in rear passenger area but I get no sound thru rest of vehicle.

99 Discovery II, SE7 model.


I know there an AMP under the seat which I swapped with another, Are there any other amps', fuses or modules I need to check or swap?

 

What's odd is the headphone jacks draw sound from the circuit powering the rear subs. On mine plugging in headphones cuts out sound from the subs but other speakers are unaffected