AV Audio In - Horrible sound, Screen breaks up?

Hello all, wasn't sure weather to post this in the Audio section or the X5 E53 section.

Anyway, after much reading on the best and or varied ways to connect an external music source to the E53 series X5.... I went back to the old trusty analogue 3.5mm connection.

At least this way it allows for our Iphones and Android phones to connect without too much trouble.

After selecting A/V via the Computer TV menu... the sound is very average and it made the screen on the TV jump all over the place.

Does anyone else suffer from this?

Is there a good sold prefered method for using phone devices for as a music source?
Or am really just better of finding a good FM transmitter

Many Thanks