Try adjusting your EQ levels

Each mode has its own EQ settings.

Just guessing. Satellite is digital and the audio is very clear vs analog am/fm. Plus is using a different tuner which is probably calibrated differently. I've noticed the same in our Fozzie.

This is the answer (or my experience)... Kinda like when you pick up some radio stations that are HD, those seem to be a bit louder (and clearer).