This issue started randomly 2 days ago.
I have the Audi Symphony with Bose and a parrot kit. I've had it for 1.5 years and I've not attempted magic of any sort.
As demonstrated in the video. Once I remove the keys from my ignition after about 3 minutes, the speakers pop quite loud and the hissing begins from the speakers. When anything that consumes power such as locking/unlocking of the doors or the lights being turns on and off the funky 8bit sounds kick off. However, the second I tap the power button the HU, it's sorted.
Right now, as my car is parked up, the HU is on probably on; chanting the sound of its people.