I really want to say how appreciative I am for all the suggestions, folks. This really is a remarkable community.
So it turned out I had less time to spend with the M60's this weekend than I had hoped, but here's what I did do:
- Removed the sub from being wired in-line with the L and R channels and put it on the LFE output.
- Completely zeroed out the "tone control" for treble and bass in the receiver.
- Set all the speaker distances properly in the receiver. (A question about speaker size later)
- Placing the sound level meter in my usual listening position, I adjusted the individual speaker levels in the receiver so that they were all at 75 dB using the pink noise test tones. They really were not far off, which may be typical, but did need very slight adjustments (I think L and R were ~1 DB and 2 dB lower than center before adjusting).
- Measured and slightly adjusted speaker positioning to assure as much symmetry as possible.
And, I have to say, it may be a psycho-"placebo" effect, but it does sound better. Not blow-me-away better, but better, cleaner. I think we're getting there.
Regarding speaker sizes: my understanding based on something (heaven knows what) I've read in the distant past was that your receiver handles bass in one of two ways based on set speaker sizes. If front L and R are set to small, no frequency below the crossover point is sent to those channels. If front L and R are set to large, frequencies below the crossover point are sent to both the front L and R AND the LFE channel. Is this right? So I thought if you had nice fronts that could go fairly low and then "bow out" gracefully when they reached their bottom, you basically wanted them getting the same frequencies that go to the sub. But some of you guys have suggested setting the M60's speaker sizes to small, which I think tells the receiver not to send them any signal below the crossover point? Am I understanding correctly? I'm sure a really nice sub has a lot more low-end than the M60's, but they aren't bad, and I'm not sure that the M60's aren't doing a better job with frequencies, down to, say, 60 Hz, than my little 8" sub is - although the sub clearly does better when it gets really low. I guess when you have nice fronts the whole small vs. large speaker size is a little unclear to me. In addition, my receiver has an ON/OFF setting called 'Double Bass', which according my best interpretation of the manual, specifies whether or not the L&R channels are fed the frequencies below the crossover (in addition to the LFE channel). In what tinkering I did, what seemed to sound best to me was setting the L and R speaker sizes to large, crossover at 100 Hz, and 'Double Bass' set to ON. Does that sound remotely correct?
Alan, thank you for your comments. I did physically remove the grills and lightly touch all the drivers to make sure they were all moving, but did not verify the operation of any driver/tweeter more closely than that. I'll try to find some good material and give it an ear test. Thank you for educating me about the "break-in" issue. I think it would be unlikely that anything was damaged by my leaving the CD changer playing during the day because I left it at a very comfortable listening level; I don't think anyone would've called it loud.
I really do think some component of what's going on here is probably the "psychological break-in" factor on my part. Today is only the 11th day I've had them, and I've not gotten to listen to them every day. In another 10 days so I want to hook the Polks back up in place of the M60's for comparison. I think the difference will be more apparent to me then.
Thanks for all the links, Ajax. Some good reading material I look forward to delving into.