hello from newbie. I've been already visiting here for a while and been learning about my 2011 C4 B7 for a while, but now my first thread.
I've already found this topic here as well. Unfortunately, only after my "action".
I happily replaced the RD5 (aux only) in my B7 darling with the RD5 L5 (with aux, usb and bluetooth).
Everything was activated via diagnostics - change vin in radio, activation of necessary functions in C-display. Display shows everything, steering wheel control works, pairing with phone works...
And now the problem (which few members here have also experienced, I searched a lot) - the quality of music via bluetooth is terrible



I read that someone solved / tried to solve it by updating the firmware in the RD5 unit - but unfortunately I didn't read anywhere how it worked out.
Please - has anyone managed to solve this somehow? Firmware update? Replacing RD5 with a more modern version? Or does it have no solution and only ugly Chinese aux things are the "solution"?