2006 XJR with audiophile(?), external power amplifier

I'm getting very low volume and tinny sound from the all of my left speakers. Right side is fine. I tried all adjustments including DSP. Makes me think the amp is bad but I'd like to check the signals going into it, just to be sure. I have wiring diags. but they only show amp output. The only connections I see between the audio unit, the CD changer and the power amp are fiber optic. Is the audio signal sent through these?

Thanks

 

Yes the only "input" to the amp is the fiber-optic signal.

I would check out the speakers, it's happened many times that the speakers fail, apparently all at the same time, bad connections at the speaker itself.

Have a look here https://www.jaguarforums.com/forum/x...006-xj8-65458/

 

Wow, very interesting thread! I will check the speakers. Thanks for the tip

 

Some cross checking with jumpers points to weak speakers, that's a surprise. The whole left side. I guess they could have been going one at a time as some have found.