Cap'n, I totally misread your post. I think sometimes because of room modes or perhaps running the sub a bit "hot", the articulation of, say, stand-up acoustic bass is perhaps a little more precise with the sub off.
So ignore some of my blather about "predicting", etc.
Alan
Yeah - I read my post again and I wasn't very clear. In an attempt to say it more clearly:
With a sub, there is more bass, and the room sounds fuller, although the bass tends to be a little bloated and amorphous.
Without the sub, the M60s are punchy and musical (notes are clearly articulable, as opposed to just a deep drone sound). It certainly doesn't go as deep, but for some music, it is preferable, as the sound stage seems a little more clear.
Comparing the "punchiness" - without a sub, it's like getting hit with a closed fist. With a sub, it's like getting steam-rolled by a bull-dozer made of pillows. The force might be the same, but the effect is different.
And thanks for the "welcome back." It had been too long.