2010 Touareg with RNS510, sat nav, reverse camera, phone and MDI connection used with iPod.
v6 TDI

Recently the iPod became very noisy, like a radio station with bad reception. Have tried another iPod with the same noise present.
Analogue radio, SD card audio quality is fine and are not presenting with the same noise.
Have tried a new iPod MDI cable with no change in the noise.

Not sure if this is only recent, but selecting MDI on the RNS, turn up the volume and you can hear a whine that increases with the revs of the engine.

Otherwise everything seems normal.
Anyone had this before of got any ideas on where to next for troubleshooting?