Hello, my Audi recently started having sound problems, the radio works it catches FM's and so on, the issue is with the sound only, when I turn the ignition on I can hear music and everything from the speakers, whenever I start the engine it's like a random number generator, sometimes the speakers will keep working, other times it won't, sometimes it will start working after driving or being in a standing still for a couple of minutes. It looks to me like a wiring problem, but what confuses me, is that if the speakers are working they will never stop working unless i turn the engine off, any ideas? Audi A3 8P 2004, BOSE.

I'd recommend a diagnostic check. Definitely an intermittent electrical fault. Could it be an issue with the Bose amp I wonder?

true  they can be a pain 

That sounds like a poor ground (earth) at the aerial.