As I sit here, sipping my glass of Monasterio de las Vinas Riserva, admiring the ebony finish on my M50s while listening to Blueberry Hill by The Dukes of Dixieland, I can't help but wonder what they would sound like with an HP driver and a mid-woofer in place of the twin woofers. They'd likely sound like the M5 with cleaner reach somewhere close to the M60. But they wouldn't be as sensitive as the M50 or M60 and likely the same price as the M60.

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