I've had trouble with loud playing musicians wanting K-240 volumes
loud enough to overcome their amps, which they insist must be right
next to them. On the way in or out of a recording session they're
likely to set that amp down on the K-240s, or roll a chair over them.
So... K-55s (closed) and K-66s (open) became what musicians got
during tracking. I reserve the K-240s for myself as one compare
point during mixing.
Of course, all of those models are obsolete. But, I'd suggest that
the idea to have "good" and "loaner" models is still valid.
G'luck....
--
Kevin