MDI Sound Quality

[AlexR1823]

So I attempted an MDI retrofit at the weekend, but the sound quality is poor through the MDI box, I know the MP3 files are fine because they play through my dads car perfectly.

I read that swapping pins may be required, I tried swapping the ground pin from 2 to 3 but that did nothing, are there any other possible fixes to this issue?

Also, found this on my-gti if it helps:
http://www.my-gti.com/1328/auxiliary-input-audio-sound-quality-problems-after-changing-head-unit

[Andy]

fitted one to mine the other week and it sounds fine

[Pashka]

Check the loom for breaks.

[StephenED30]

Try going into the settings, somewhere the input is set to low, try it on medium or even high. see if it makes a difference, it did on mine. 

[AlexR1823]

Checked the loom and can't see anything obvious.

Also there is no option for AUX input level? Checked in all the settings and cant find anything.