Radio Loss of Volume

[Christopher]

Hi, hope someone can help.
The head unit in my "58" plate MK7 has lost volume. If all the controls are set to maximum volume, the sound from the speakers can just be heard suggesting that the volume controls are still functioning normally. The unit fitted is the one with two plugs plus aerial connector. There is no bluetooth or phone connection.

The radio/CD/AUX etc all suffer from the same symptom.

They were all working normally when the vehicle was parked up before going on holiday. Upon our return the fault was there, drastically reduced volume.

I have checked the resistance of the speakers, they are normal 4 Ohms and 8 Ohms for the tweeters. Rear speakers are not fitted.
Unfortunately I cannot seem to find a wiring diagram for the interconnections or a technical description outlining how the volume control functions.

Has any one else experienced the same symptoms? -if so, how was the fault cured?

thanks
Chris