As a long time 2-channel enthusiast, I really had no choice a while back (maybe 10+ years ago?) but to succumb to 5.1, in light of me not having a separate dedicated music listening room and another dedicated home theater: i have a living room that doubles as both.
I have the Onkyo 929 (previous Onkyo 3008, but it fried last week, yet another casualty of the Network/HDMI board fiasco) now, and i use 7.1: the usual 5.1 + Front Highs. (I know the adage of wide before highs, but my room doesn't allow for front wides) I used Audyssey MultEQ X32 with 8 listening measuring points. One single subwoofer, but a highly accurate one from Revel. I often fear the complexities introduced with 2 subwoofers, plus, i really don't need more than the one uber powerful Revel subwoofer.
In doing my set up, i listened a bit more critically, similar to when i did during the 2-channel days, and discovered that of the many "listening modes" available on my new Onkyo 929, some modes direct FAR TOO MUCH to the Center Speaker!
I thought that since PLIIz is marketed to claim special benefits for Front High speakers, that it would be especially well suited for me. Instead, i discovered that for most music with vocals, way way too much of the human voice is directed to the Center Channel speaker!
After trying many of the modes, I then discovered that some of them, i.e. DTS NeoX Music, would have an OVERLY LAID BACK presentation, i.e. the voice recedes way way into the background, too much so!! In the parlance of high end 2-channel audio days, one would call that a "Row S presentation" or "Row Z presentation" or similar. It sounded artificially receded -- the voice portion, that is. On the other hand, if one were not sitting in a sweetspot, and say, one were milling about the Living Room, getting something to drink, or just simply NOT in the sweetspot listening position, this laid back, receded voice presentation actually presented a more pleasant sound field, however UNrealistic, UNintended by the original sound engineers!! How odd and unexpected. I say unintended by the original recording engineers because if one were to choose 2-channel or Pure Direct, or something akin to direct output sans processing, one would hear a far more up front, i.e. a "Row B or Row D presentation", so one may confidently conclude that THAT was the original intent of the recording engineer.
So...I don't know which listening mode to select!
I DO know that those modes which direct too much voice to the center channel speaker would be undesirable. My center channel speaker sounded like it was taking 90% of the load of the voice, if not the entire music track as well! i.e. the other speakers were not doing much whatsoever in modes like PLIIz.
May I ask for some advice, some recommendations, some direction please on this topic?