Hi there. I'm trying to find out if someone has had similar experience as I have before I go to the dealer.

Got myself a new 2013 A3 (3door) about a month ago. Had the Bang & Olufsen sound system factory fitted.
Problems started about a week ago where I completely lose sound. (Media, Radio, BT... the whole shebang).
After driving for about 30min in damp/rainy weather the sound starts 'flickering' on and off at 1 second intervals. It goes on for a few more minutes where the 'up'/'down' intervals gradually become shorter and shorter until sound completely dissapears.
It does not matter in which MMI mode I am. The core sound connection drops away. The MMI continues to work though. The volume changer stops responding when the sound is down but briefly works again when the sound goes up.

I went to the MMI 'Sound Settings' when the above behavious started and I witnessed the different dials (Sub, Bass, Trebble, Gala, Surround, etc...) also going 'grey' (inactive) when the sound goes down. I.e. they flash active/inactive in sync with the sound appearing/dissapearing. This tells me the MMI system is losing it's connection to the B&O control system.

No water is getting into any visible parts of the car. The fuse box is dry. The amp is under the passenger seat so I don't see how water can affect it there. I've reset the MMI. I've restarted the car. It only start working again after the car has been off for a few hours.

I can't replicate this at will so I already know I'm going to have problems convincing the dealer. Any ideas or 'gut feels' as to what could be the cause? Any suggestions would be much appreciated.