Jim,
Although the MBLs are mainly known for their spectacularly realistic 3D imaging and soundstaging, that isn't the first thing that attracted me to them. It was actually the tone and timbral realism (to my ears).
They sound open and realistic, and just seem to be able to re-create the different timbral qualities - from the solidity, and metallic quality of a struck chime or bell, or drum cymbal, to the brassiness of a horn, reediness of a sax, plastic/gut string of classical guitars, the golden sparkle of a regular acoustic guitar, etc. Sounds are just more varied - and closer to the real thing - through the MBLs, in my experience. And their resolution is second to none. There is a relaxed, completely effortless level of resolution - the type that makes sounds actually more organic than the type that says "wow, listen to that tweeter!" that makes regular speakers sound like they are "trying."
Add that to the utter lack of box sound and the most realistic dimensional imaging around, and they are just more realistic sounding than just about any speaker I've encountered. They make other speakers sound like "tweeters and cones in a box" by comparison, and they have a solidity to the sound that is more like a dynamic speaker rather than the thinner ghostly quality of most panel speakers. They are the whole package.
Whenever I listen to the MBLs and go back to my box speakers, it takes a while to adjust back to tweeters 'n cones in a box.
That said, of course nothing is perfect and I have various other speakers for a reason. Speakers sound different and I like those differences.
The MBLs, if not in the proper room and on the right electronics can get a bit "icey" in the top end. But when controlled, that goes away leaving the rainbow of timbral colors.
