I have a general question about surround sound.

What is the big deal about multichannel music? I see where many of the new SACD's are multichannel. Does this make the recording seem more lifelike? When we go to a concert, the music only comes from in front of us. Isn't that the purpose of the two speakers in our stereo systems? Why do we need two behind us? I understand about ambient noise, reflections, etc. It just seems to me that music is more accurately reproduced with two channels rather than multichannel. Could I please get some feedback and whether you agree or disagree with me and why.
I guess I kind of feel like you are under estimating reflections. A reflection can sound as lifelike and be dynamic as direct sound. To me, that is the point of multichannel music. Although I have not adopted it yet.
I love two channel also, but multi-channel can be good if it's done right.
A lot of multi-channel mixes are stupid, putting instruments and singers behind you. The good ones put you in the audience, like at a live performance, but that does not mean it isn't accurate; the fronts do the same as always, the rears add the ambience of the venue. You hear the sound of the room, which can be good or bad: concert hall good, arena bad!!
Actually, at a live concert, the sound comes from all around your head through reflections. The directional cues that you relate to come from the front only. The richness of the acoustic experience relies on accurate rendition of stage depth and reflections in the listening environment, usually a larger one than a home. Incredible expense and art have gone into designing concert halls to provide the best acoustics. Two channels can only present a window into the direct sound with perhaps some stage depth. If you use multichannel to deliver the appropriate sonic environment, than yes, it is superior to two channel. Multichannel has the benefit of stabilizing bass and midrange and reducing summing and cancelling nodes, making these tones much more rich and believable.
It is impossible for two channels in front alone to present a complete acoustic experience and this has been demonstrated through psychoacoustic research, although some audiophiles cling to the notion that somehow two channels are always the best.
The thing is, when you get your 2-channel right, you do feel enveloped by the music - in the correct way. That is up to us to discover the tweaks (room treatments etc) that get us there. With multi-channel, you are at the mercy of the mixing engineers who want to "Whizz-Bang" listeners with things like tambourines in the rear channels.