First off, thanks again to one and all for the suggestions.

I spent some more time last night experimenting with various settings - M60s set to SMALL with several crossovers, M60s LARGE with sub set to varying crossovers and just LFE. With my HK 525 I can set the mains to SMALL and specify individual crossovers for mains and sub. With the mains set to LARGE I can set the sub to be SUB, SUB (LFE), or SUB + L/R, the latter having a synchronized crossover with the mains.

I am wondering if the crossover on my receiver is working correctly. With the M60s set to small and both the speakers and sub crossed at 80Hz (these can be set independently), a low freqency sweep produces a significant amount of air flow from the ports of the M60s below 40Hz. Could this be the M60 drivers responding to the air moved by the sub output?

Taking the advice from an earlier post I took a different approach to lowering the crossover - M60s set to LARGE and the sub set to 'SUB + L/R' with a 60Hz crossover - Holy S***! - serious difference in sound (very different with than having the M60s set to small with the same crossover)- much more transparent blend, much less localiztion, and MUCH more low end support. It was pretty late and at that point I just wanted to relish the new sound. I need to get AVIA back out and check the output.

Sushi,

I had submitted a diagram of my room to Dr Hsu prior to buying it and it's currently in the location he'd suggested. I've tried Alan's crawling method and tried a couple other locations and found this location produced the best output, but it could also be exaggerating the room nodes.

The nodes seem to differ between LF and RF, with a LF+SUB sweep, the big node come about between 70Hz and 80Hz, which lead me to believe it was a crossover problem. But with a RF+SUB sweep, the big node was up in the 90Hz to 100Hz. Then with both I seem to have a pretty significant (+10dB)dip between 40Hz and 50Hz.

I'll try moving the sub and further experiment with the output mode and phase options now that I've found a better speaker/sub configuration and see if that tames the nodes.

Thanks!