zoom25, good choices!
KEF LS50 should work well in theory as the drivers are not only coaxial, but coincidental (voice coils aligned in all three dimensions. But based on short listens I've never been impressed by the sound. However the LS50 wireless (which is active) is reportedly far superior. If phase between woofer and tweeter is accounted for should be nearly ideal (a cone and dome can not be expected to sound the same at the crossover frequency).
Omega should be nearly ideal too, but haven't been able to hear one with the current drivers.
Both of these are largish for a 2 foot distance.
Have been racking my old brain for the name of a very small high quality single driver speaker (with built-in amp and subwoofer output) intended for desktop use, around $500/pair. They came in a couple of different cabinet shapes made of bamboo and leather and as I recall were from Canada. Maybe someone else can think of the name. Don't know if they're still in business as it was a few years back.