997.1 Head unit/ Bose amp problem

[Urban67]

I have an 08 997 turbo, which is a great car apart from the old PCM unit which I replaced with a Pioneer Avic f88 dab four years ago. Recently the sound started to just cut out completely but the head unit still appears to be working absolutely fine. This happened a few times, when I restart the car the audio works fine but now it has stopped altogether.
My thought is that it could be the Bose amp malfunctioning. Has anyone had any issues with this?
Also, where is the amplifier located and does anyone know of where I could have it tested and repaired?