It doesn't really require a coherent light source, although that does allow further miniaturization.

I think it would be fair to allow a hypothetical 1920s CD player to occupy most of a room. I'd be interested to see exactly how hard it would be to produce such a thing using the available technology of the era, though I'm still somewhat skeptical regarding the complexity and precision required of the laser motor (which unlike a vinyl needle needs to be controlled manually, rather than just following a groove mechanically) and the spindle motor (which needs to accelerate precisely depending on the laser's distance from the center, unlike a record which revolves at a constant rate).