[HaychM140i]

I have a 2018 M140i shadow edition covered 42k miles.
Now this is really bothering me and ruins the whole driving experience and if someone could help me sort this issue out I’d be very grateful! So the Harman kardon speakers work when car is idle, as soon as you drive the sound cuts in and out fast until your gears change and rpms drop to 1k. At 1k rpms the Audio works perfect! As soon as u accelerate above 1k rpms whether you floor it or gently accelerate the audio cuts in and out fast. It’s bothering me and I don’t feel like driving the car because I like to drive with loud music. I’ve had the car 5 months and it’s been doing it ever since I got it. Was rear end damage but I don’t see why that would be the cause. Can anybody help me? I have to wait till I’m at 30mph 4th gear @ 1k rpms just to hear the sound. What could it be? Wiring in the boot looks ok. Could it be the battery or auxiliary battery?