Amplifier click in the trunk

Hello.

I am fresh A8 owner and find this forum super interesting. I could use some tips. But now I have a problem that I have not yet found a solution to.
My A8 has a Bose system, the original phone, and a radio concert. As long as the radio is running, everything is great, but if the radio is turned off at the switch or via the ignition key, the Bose amplifier in the trunk clicks like a flash relay (even in the same clock). Then I tried another amplifier ---> same problem, only the clock was faster.
Now I am a little perplexed and hope that perhaps one of the experts can help me.