Hi, I'm new to this forum, I've been using it as advice and suggestions for the last couple of months but finally decided to make an account. I've been having an issue with the sound system in my 2005 530i. That sounds very broad but I don't know how exactly to explain it. Whenever I put my key in the ignition about 5-10 seconds after, there is usually a really loud static-like noise which is then followed by a noise as if someone is knocking on my window, that comes from the trunk. After that, the radio system is either stuck on mute or it works fine. Please let me know with any suggestions, I've heard that it's possibly the amps.