Sim sound attenuates when FSDT Basel scenery installed

[Grup]

Can anyone offer help, please? I have had to uninstall LFSB as there is a strange conflict that attenuates the sound of the sim. Sometimes the volume returns to normal for a short while then reduces to low level. Once the scenery is uninstalled, the volume remains constant (normal). When i look in Windows settings (Sound), the P3D fader/slider involuntarily reduces the sound level making the scenery unusable. Is there a fix for this? Am using P3Dv5.3 with FSL A320.

[virtuali]

Nothing in the scenery controls the sound volume of the sim. The Couatl engine, which all our sceneries use, has its own separate sound engine, with its own separate volume slider in the Windows sound Mixer, precisely for the reason it won't affect the simulator sound.

What is happening, instead, might be Windows itself, that has lowered the sound, because it thinks the simulator window went out of focus, see here for example:

https://www.avsim.com/forums/topic/547541-prepar3d-v44-lowering-the-sound-from-background-apps/