I don't know the answer to that one.

That Brubeck tune is an interesting one. On the actives in stereo, the music on the left appears panned hard left which means it sounds like it's coming out of the left speaker. On the M5s, that's not the case. The music appears behind the M5 as if there is no speaker there - or rather there's a speaker but it's projecting the sound backwards right behind it. That's the effect when the M5s are 12 feet apart, I sit 14 feet away and the tweeters are about 6" below my ears. As soon as I raise them to ear level, the music again collapses into the left speaker.

There are other tunes that create a similar difference between the actives and the M5s.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated