is a center channel really necessary??

thanks for all the thoughtful responses so far. Just to clarify, I am debating 2.1 w/ stereo integrated vs 5.1w/ AVR (not 4.1 vs. 5.1), so Byroncunningham brings up a good point. Sounds like you DO lose alot with a two channel downmix.

And it's not just about sound quality, 5.1 will require more boxes around the room that is a multipurpose family room and as much as I like killer sound systems, there's an aesthetic issue here.

One thought if I go 5.1 is to put the surrounds in the ceiling, which takes away two boxes, but still leave 3 for the front stage which will sit on top of a built-in cabinet (maybe 24" deep)..

I agree with Shadorne that 4.1 is much preferrable to 2.1 for an enjoyable movie experience. I also agree that a poor mix down can make the dialogue hard to understand. But in my experience you don't need to spend a ton of money to get a pre/pro or receiver that will do a good job on the mixdown. My mid-range Pioneer Elite receiver does a fine job with the mix down. Not quite as good as my old Bel Canto Pre/Pro, but dialogue is always clear. Very important is to have good speakers of course.

So far we've only talked about 5.1 in a movie application. What about multichannel SACD? IMHO, ya gotta have the center to create most coherent sound wall across the front in MCH. I have my system set-up for 2CH, with HT bypass => AH tube buffer => monos, 5.1 HT using DSP, and 5.1 MCH SACD with discreet analog out (vs HDMI). Formerly did 2CH with dedicated CDP, but now moving to a one-box solution with MW modded Oppo BDP-83. For $1,500 (which includes player) everything is covered ... movies, 2CH, and Multi. So going 5.1 with SACD, there's no mix down, and there is a fair amount of information to be captured from the center channel.

Then there is the guy who ignores all of the typical rules,
of Audio...Me.

IMHO, I use the "center channel", but
not with ANY decoders, just "full range".

In addition, I employ dual speakers for Both Front & Rear,
Center channels.

So there is effectively, the same speaker cone sizes of
of just shy of two 15" cones, for Both Front and Rear.

Not only do movies, sound more "accurate, and life-like",
but the Music too, is greatly enhanced with the addition

of the Center speakers.

Being a die-hard, 2 channel man, I simply use 2 independent,
stereo set-ups, 1 in front, and the other in the rear,
and I use 2 side speakers.

I could remove the Center speakers, but then, the "room"
is no longer, "locked in sound". But then...

The mains need more juice, to make up for the -6db.(just front)
auditory effect, left removing Both Center speakers.

The sound is more "directional" without the Center speakers.

The Center, and sides, are like "whipped cream, and nuts"
on a ice cream sundae.

They seem to just "top off" the sound experience, without
any decoders, just "dual Stereo", which is the most
Natural "Surround" Sound I know of.

YES, I have "butt ugly" speakers , I admit it, but lucky for me, Music is about "Hearing" not "Seeing".

Although, to many, the mind is made up, at the Brand(Krell),
weight(140lbs) , review(John Atkinson),or any other number of ways, available,to learn of a "Product"

And "LOOKS!" mean Everything!

I care ONLY how it sounds.

Hearing IS Believing!

I Love My Music!

Period.

Forgot to mention ... similar to Bjpd57a1, MCH for SACD is run External Direct, with no signal processing.,