Waveform Mach Solo.
These were the smaller version of the mighty Mach 17s - famous for their egg-module head containing the midrange and tweeter - that John Otvos sold for only a short time before he closed his company. Very, very few were made and sold. I reviewed them at one point in my room and they were stunning, both in looks and sound. But...didn't buy them at the time.
A few years back I grabbed some second hand Waveform Mach MC monitors from audiogon - essentially just the egg module of the Mack 17/Mach Solo. Whenever I set those up and listen I'm just taken aback at their incredible combination of neutrality, natural warmth of timbre, boxless soundstaging and liveliness. Make me pine for the floor stander Mach Solos which had incredible bass. But...they pretty much never appear on the used market.