Pre-cueing with USB-Headphones

I’d like to use djay on my Surface Pro 5.

My master-audio output will be simply via the headphone jack. I’d like to use USB headphones to pre-cue tracks. While it perfectly works to select between Surface-internal Audio and the external usb device it is not possible to have both.

Any plans to work on that issue? I’d really love to work with that minimalistic setup…

BR
Gregor