Send to-option does not work for me. I tried and it is fine if you play 1 song at a time and send each song right after the previous one finished. At least I could not get it to work with older Musicbee, Foobar2000, or XMPlay. XMplay opened a new instance for each file; Foobar and Musicbee replaced Now Playing playlist with a new list of the file(s) I sent, instead of just adding them to the queue.
I don't actually need 2 big decks like Serato, or MIXXX, or VirtualDJ, or Traktor..or CUE/feature. I just need a plugin within Musicbee that allows me to scroll through the same library I use to play already.. I just want to browse to different folders, preview a song, and if I like it, I add it to the Now Playing list. Someone had made such a plugin to Mediamonkey long time ago but I don't like Mediamonkey (and the plugin is old and doesn't work beatifully anymore).
Check Mixxx.. It has crazy many decks available but the point is you have this little miniplayer on the side and you assign it a different output in the preferences.