Sorry for not explaining myself properly.
In Musicbee, I saw the outputs:
I was looking in that list for an option for Musicbee just to play through whatever default playback device was set in Windows, whether it be my RealTek mobo chip, Dragonfly usb DAC, or my instrument interface (with its own ASIO driver), rather than choose one specific output.
I thought that if I chose Directsound or WASAPI, MBee would only output to my Realtek and Dragonfly. So every time I disconnected my instrument interface, I would have to go into MBee settings and manually change it from ASIO to WASAPI.
However, as Steven said, if I choose WASAPI -> Primary Sound Driver, then MBee will use whatever playback output is currently set in windows, including the ASIO driver.