Front tweeters only play audio through radio

[osnowdeal]

Today I realized that my front speakers, in the corner of the window, only play audio when listening to music on the radio stations.

I usually listen to music through a Bluetooth audio jack connection, through the aux port, and I’ve noticed before that the front window speakers don’t play audio through Bluetooth.

They play loud and clear when listening to the radio, and even when playing the same song, it’s night and day.

Does anyone know why this is happening or have experienced this? Not necessarily an issue, but it’s bugging me.

I have an 2008 E92 328xi.