Help! Volume loss from Aux input

[3carmonte]

The radio still plays at the same volume but right in the middle of a song on my MP3 player, the Aux volume dropped by I'd say half. The MP3 player has a volume output setting but that's the same as it was and if I plug it into my Sony truck radio (as I do on weekends) it plays at the normal volume. The problem is in the MK5 but is it the head unit? Is there some VAGCOM parameter that could have gone pluey? I have no way to look into this other than a) Go to the dealer or b) Take out the Head Unit and send it out to be checked. Suggestions? The center "Radio Station frequency" portion of the LCD display has lost it's back-lighting also.

01/17/17 - Removed the Head Unit from the dash and shipped it out to: http://www.cd4car.com/volkswagen-golf-jetta-radio-mp3-6-disc-cd-changer-1k0035180d-2005-2009/ for analysis. They will either repair it or send me a new or reconditioned one back. Found out from the label on the chassis that it is a "Premium 7" system meaning it has an amp that drives seven speakers in the car. I always liked the sound from the system. I'll be happy when it's fixed! (No aftermarket solution seemed as attractive).

01/27/17 - Head unit is repaired and being returned via UPS Ground. Cost including shipping $199.00

01/31/17 - UPS delivery of repaired head unit.

02/03/17 - Installed in dash and tested. All issues resolved. The entire control panel was replaced for the LCD outage.

 

[3carmonte]

Updated original record. Also, all I have is the Head Unit. There is no "outboard" amp/controller under the seats or anywhere. The guy I bought the car from said it was a base model and did not have a premium sound sound system.