Audio: Bluetooth vs Passthrough

I have my PC connected to an AVR through S/PDIF and use Kodi’s passthrough option to allow the AVR to decode DD and DTS. I’ve recently added a Bluetooth transmitter (Avantree Leaf) so I can use BT headphones, and it shows up as a USB sound card. I can switch the Windows default playback device between S/PDIF and the new “Speakers” device with a hotkey. When I start WMC, it picks up on this, but Kodi does not. Kodi continues to send encoded formats to the AVR. How to solve? (To be clear, I’m switching devices when neither program is running.)