I get what the OP is saying. I take along one or two of the little self-powered Fostex speakers, Fostex 6301NB, sometimes when I am in a space backstage. I never use them to represent a mix or to do critical listen but more to have some sense of what is happening on stage without needing to wear my phones all day. Sometimes just one from the mono output on my panel just for me, or sometimes a stereo pair that can do a quick playback for the musos after the show. I have been surprised by the nice reaction that I get letting the folks hear a bit of their performance right after the come off stage. They are frequently jazzed and the vibe back stage is really cool. Not technical, but maybe a benefit to the day.

These things are small and reasonably light weight. Two of them fit in a small Pelican along with AC cords and short XLR jumpers. Easy.

Oh, and they even sound okay.

D.