In MPC-BE, it is possible to assign the Primary Sound Driver as Sound Device for the WASAPI Exclusive mode. For example, when playing video/audio with speaker, after a headphone plug in, audio will play on the headphone seamlessly.
Also, there is an option "Release device when idle" in MPC-BE, which release device when the playback is paused. It is annoying that you need to seek back where the music stopped when you have to listen to something else for a moment.
I wish that the above two mentioned options will be implemented. Thank you.