Been playing with my new 990, with 2 channel music (CD's); trying to figure out what the different 2-channel "surround" modes are doing (7-channel stereo, DTS Neo 6 music, Dolby PLIIx music).

As an experiment, I cut the power to the amps feeding my main speakers, so I could better hear what was being sent to the other channels.

In a nutshell: not much at all. I don't have a decibel meter, but the mains are definitely driving %80 of the sound in the room. The only mode that's seems to be sending much of anything to the other speakers is 7-channel stereo; and the level going to the sides/rear is much much lower than what's going to the mains.

Just want to make sure this is the expected behavior for the 990. Makes sense in a way, that the mains would be providing most of the sound- with the other channels just providing a little "support". But what makes me wonder a bit is a blurb in the manual- stating that 7-channel stereo is good for parties and such because of the way it fills a room from any listening position. Based on that, it almost seems like nearly the same level output should be going to all 7 channels... I'm nowhere close.

Been through the auto-calibration several times. Right now I've got a mix of balanced and un-balanced connections to the amps... but I've tried it all "unbalanced" (with a re-cal of course) and it didn't seem to make much difference.

I experienced just the opposite when I moved from my old Denon AVR-5600 to separates with the 990 -- much more content from the surrounds with the 990. I have one amp for L/R and another for all else, so I have done the same listening test as you describe.

OTOH, I didn't have much luck with autocalibration, so I did the level setup manually with my RS SPL meter.

I'm not surprised that NEO6 and Pro Logic IIx are keeping a large portion of the signal in the mains - steering too much elsewhere can sometimes sound a bit odd. I haven't used 7-channel stereo enough to know just how the signal distribution breaks down.

How are you measuring the levels? If you stayed at the same volume setting and went from measuring the levels in stereo, then cut the mains off and measured the levels of the same passage from just surrounds and center I'd expect the overall reading to drop - the reading with all seven speakers running might be somewhat higher, but there is probably some signal reduction happening. If they took one signal and sent it to three speakers (right going to right, right surround, and right surround back) without any decrease in level, the three speakers' outputs would add and would come across as significantly louder at the same volume setting. I wouldn't be surprised to see a 3-6dB or more drop in individual channel levels compared to individual channels under stereo mode. Like I said, though, I haven't spent much time with 7 stereo and am just sort of theorizing here - others who have more experience with it may have better explanations of what it is doing.

Just my two cents if I may, I use 7 channel stereo for my cd listening, and the sound seems to be coming from all speakers evenly, had to turn down the right surround and right surround back as they are behind and to the side of my seat at 5 to 6 feet, calibrated manually to 70 db with radio shack meter, but like I said those two sounded louder because they are so close, didn't try what redrob did with shuting off mains thou, hope I helped

Fixed.
I went and checked the calibration levels, and the sides/rear were all set to zero (which I knew to be incorrect). I did a manual balance, and things seem to be working a whole lot better.

Why was is messed up? Well, the auto setup routine is grumpy about the speaker sizes. It incorrectly detects the fronts as small (Klipsch Cornwalls are definitely not small), which seems to be precluding getting the auto levels saved, since it is correctly detecting my sides (Klipsch Heresy's) as large. It looks like I'm supposed to be able to "ignore" the error, but I am unable to select that, and so I end up without the calibration working.

For now, I'll have to do manual configuration (have to re-do it, as trying the auto thing again just screwed up my manual settings).

The Cornwalls are certainly big speakers, but if you have a sub in the mix you might give "small" and a 40Hz or even 60Hz crossover a try - the lower limit of the Cornwalls appears to be around 35Hz. My Studio 60's have a -3dB point of around 30Hz, and I've had some good luck with running them small and crossing them over at 60Hz or so.

OK, so I guess it's time to ask my dumb question. If I set the crossover frequency to, let's say, 40Hz. Then, what is the difference between setting the speaker size to small or large?

I don't have it in front of me, but the system settings now look something like:

Front: large/40Hz
Center: large/80Hz
Side: large/80Hz
Rear: small/160Hz
Sub: LFE

What would change, if I set the front/center/side to "small"?

If the fronts are large, then the crossover point is ignored. If you want to use the crossover, you need to set the speaker to small. The Heresy's only go down to around 63Hz based on some info that google turned up for me, so I would definitely set the sides to small. The same is probably also true for the center.

That's sort of what I was guessing, but wanted to be sure. It would be a bit clearer if the cross-overpoint was just "N/A" or something when speaker size was set to large.

Sides are actually Klipsch "HIP" (Heresy Industrial Ported), which have a little better bass response than the consumer Heresy- but I think your advice is spot on.

Looks like I've got more tinkerin' to do :-)