Thanks Bob. I really do appreciate the time and effort you put aside with your very comprehensive reply. Awesome. Thank you so much! and most informative.
Now I understand "room modes" a lot better.
I am using the the Anti Mode 8033 in tandem with the Yamaha YPOA for the following reasons Mr. Kalman Rubinson from Stereophile magazine mentions in the end of his review of the Yamaha CXA-5000 and he says this;
"A look at the graphic presentation of YPAO's correction results revealed all (fig.1). All of the correction filters were of low Q (ie, broad in frequency), and there was little correction in the low end. One of the L/C/R channels now had a filter at 63.1Hz, but the rest were at 78.7Hz or above. No filters below 125Hz were applied to the L/R surround channels, even though their placements in the room's corners subject them to a severe diagonal room mode near 45Hz. Nor were any filters applied to the subwoofers below 125Hz; with the Yamaha's bass management applied at 40Hz (fronts) and 80Hz (surrounds), this meant that YPAO was not applying EQ below 100Hz.
Even knowing that, and despite its lack of effect on the lows, I continued to prefer YPAO-Natural to Through (no EQ at all), for the former's natural-sounding mids and highs. YPAO has filters that can have their center frequency set as low as 31.3Hz, and a more-than-adequate range of gain and Q, so it could be used for the bassbut it seems that the correction algorithm made no use of these filters. This left me with three options: 1) I could use the RoomEQ Wizard, Omnimic, or XTZPro room-optimization software to measure and develop bass filters to add to YPAO's results; 2) I could add an external subwoofer equalizer; or 3) I could accept the Yamaha's settings and say that, although the Aventage CX-A5000 is an excellent, transparent, capable pre-pro, in this aspect it is flawed."
This is why I felt that the Anti-mode 8033 would go some way in solving the above shortcomings of the YPOA. It certainly seems effective..
There is only one more thing you mentioned Bob, that I do not fully understand, even after studying the Harman Kardon link. Why is it that you think that having my bookshelf speakers mounted on the subs is not ideal?
Is it that you think, (In layman's language) that the vibration from the subs might interfere with the sats?