P3D4.5 HF3 Volume Issues w/ GSX (and others?)

Hi

Not sure where I should go first with this issue, so I thought I'd try here for suggestions.

I'm using P3D 4.5 w/HF3 and have recently reinstalled my entire OS, P3D and add-ons (I performed a complete drive wipe first).

I'm using headphone through my monitor, which is being fed by a HDMI cable coming out of my GTX970.  I'm using nVidia driver version 26.21.14.3200.  Looks like it's making me use nVidia sound drivers - there are no other options in Sound Settings (NS-40D510NA15 Monitor is my only playback option, using NVIDIA HD Audio as a controller).

Here the issue: I get volume swells and dips when using GSX on passenger load, etc. By this I mean that passenger loading sounds come in extreme loudly, and then drop out when using P3D ATC, and then come back in again 30 seconds later.

I used to manage these issues using two methods:

1) Sound Control panel => Communications => Do nothing selection

2) Right-click on NS-40D510NA15 => Properties => uncheck Allow applications to take exclusive control AND => Enhancements => Disable all enhancements

Used to work, now it doesn't.  And it's not just GSX (couatl scripting engine) - anything running external to P3D using sound will be affected in some way.

Any ideas on what to do, or which support forum to go to? (P3D, GSX, NVIDIA, Windows, etc?)

Thanks for your help,

Daniel