Dean, very interesting. Maybe I misunderstood one of your observations, but it's one of the basic DPLIIz points that opting for front heights rather than back surrounds would be advantageous especially for someone sitting near the back wall without enough room for a good rear sound field to form.
I probably wasn’t clear about what I was saying. With Dolby PLIIz engaged both the surround back and height speakers are active if connected. So it’s not an either use the heights or the backs situation both can be active using PLIIz. However none of the Dolby settings on this receiver line allow you to use the Audyssey DSX wide speakers if height speakers were connected during auto setup. It won’t even default back to PLIIx at all if height speakers are hooked up. OTOH Neo 6 allows the DSX wide speakers to play along with the backs even if height speakers were connected during setup, but doesn’t give any option to use the height speakers if the wides were connected during setup.
So in order to do A/B/C comparisons between standard 6.1, standard 6.1 + heights and standard 6.1 + wide I had to use Neo 6, PLIIz, and Neo 6 + DSX respectively. I could only do 8.1 and not 9.1 due to lack of speakers but the system is capable of driving a full 9.1 but just not the wide and height speakers at the same time.
I’m not sure if the inability to use both height and wide speakers in place of using surround backs is hard wired or something they can update later in the firmware. You’d think since the surround backs can be reassigned to another zone or bridged to the mains you could also reassign them to support either the height or wide channels but it doesn’t seem to work that way unless I’m missing something in the setup but the manual clearly states that you can’t get sound from the heights and wides at the same time.
Right now I have it hooked up in a 9.1 configuration (standard 7.1 plus two M22s as DSX wide speakers). I liked the effect of the height speakers better but they didn’t seem to come into play as much as the wide speakers. So the wide speakers seemed to have more overall impact but it wasn’t as noticeable when they were missing. Now I’m going to give each one a try for some time with a range of material not just my demo stuff to see which one seems better over time and not just when A/B testing them.
My preliminary judgment is that I wouldn’t rush out to buy any new speakers to upgrade. There may be some setups that would benefit more than my room. So now I’m hoping to see if after getting use to these new modes if things just sound wrong when they’re missing. I think that will be a better way to determine if they are worth buying the extra speakers.