I'm pretty sure I'm not losing my mind or my hearing-- SV is auto-ducking my music track for other sounds. I'm hearing the volume increase between dialogue, and decrease for things like sound effects. Is this possible?
Vegas doesn't do this.
But some audio drivers may do some kind of normalization by default, which in effect is the same.
On my notebook I had to dig into a lot of settings on audio, until I could get rid of this behavior.