Wow, great stuff! Time to get the disc back out and play with some of the tones I didn't bother with initially...
Reference Mr. Kuo's general recommendation to set all speakers to small because "most" mains can't reproduce the lows as well as a dedicated sub, I couldn't agree more. But the key word is "most." Thinkly's mains have 12" woofers, and mine have 15"! They have no problem reproducing better bass than any sub my budget could handle (grin).
Which leads to my next comment: Since my setup currently uses no dedicated sub, all my low frequencies are going to my Large speakers (the two mains and the surround two satellite-sub combo). This set me squarely on top of Mr. Kuo's general remark that "you usually don't have an ability to independently adjust the strength of bass coming from each main channel." But that's an easy situation to fix. As I keep preaching, buy an equalizer! Piece of cake.
Thinkly, check out the section of Sonnie's post about phase alignments. Note where it mentions specific drop-outs of certain freqencies? That's another possible cause of your frequency sweep question in your initial post. I still tend to think my original guess about your room's acoustics is the culprit, though, since the differences appeared between the left and right channels rather than across all speakers.
