Hi @Dunlock
Thanks for sharing the system information.
On the system on which I am testing, audio continues to be on with FxSound when monitor is off and display is locked. Audio goes off when the system enters standby state.
I would like to confirm if your PC supports modern standby (S0 low-power idle), and if we have to handle the sleep states differently.
Can you please run this command and share us the output?
powercfg /a