Interesting, Steve. Thank you for this.
I have been doing a bit of research this evening. I checked another speaker in the A6, one constant on the labelling (along with the Audi logo) is the brand name “PSS”. If I were to give them the benefit of the doubt, you could say this stands for “Premium Sound System” [from B&O]. However, like you have shown in those photos, older Audi B&O systems had the B&O logo on them.
A quick Google of “Audi PSS” brought me to this page: https://www.premiumsoundsolutions.com/business-line/automotive/
Along with that, I checked the B&O site with information on the Audi systems: https://corporate.bang-olufsen.com/en/partners/automotive/audi/a6
The B&O website makes no reference to them providing the hardware at all. It’s all about the 3D sound, VNC (Vehicle Noise Compensation) and positioning of the speakers.
I would appreciate some clarification from Audi on this, so will be sending this detail and asking whether this assumption is right. It’s that, or don’t have the B&O system in my car and a retrofit will be in order (at their expense).