All:
I recognize the burn-in issue is likely legitimate (though I have read of folks who loved their Hawks' sound out of the box). Ideally, I should stop posting, burn the speakers in for another 350-400 hours or so, then post results. I'll make that part of the process, but I will also try some of the other "low-hanging fruit" ideas that you have suggested.
I just switched polarities on one speaker (mb1audio). When switched, the sound in the mids became super-forward (soundstage) and loud, while the low bass became muddy. Upper-bass became more forward in the soundstage, too. I did not notice much difference in the highs, if any. Possibly some of the mid-highs came out more volume-wise. Most of the highs still felt buried. The top end of the highs remained muted, for example. I switched back and forth several times to confirm my impressions. I conclude I had the speakers in phase alignment on my original setup. Whew.
Thoughts?
I will next reset the gear to take out all power conditioning and surge protection, per suggestion--this one is not immediately intuitive to me, but it's relatively easy to try. Stay tuned. -B