A small "Spotify A/B" app

Someone capable should make this : a Reaper utility running a tiny webapp, pulling audio through the Spotify API, and it simply lets you A/B Spotify vs your Master Bus (for example). There's open-source Spotify players out there, I wonder if they could be incorporated into a Reaper utility that simply A/Bs itself (Spotify) vs the channel its inserted on. Control could still be done from the main Spotify app. I'd imagine setting a song on loop and just having it there as an instant A/B resource while mixing/producing. Of course this can be enhanced with loop points etc, but even just wondering if the most basic version of this is feasible?

i understand your use case now... makes sense now

apologies for going off on the tangent i did... i was thinking along the lines of track A track B rather than loop points for a single track A <--> B

sorry for my confusion but how can you a/b a commercial track? Are you the creator? or Are you looking to compare your ORIGINAL track to the spotify mastering algorithm? Not sure I care that much but just a little confused as to what "A/B" means in this context.