as a supplement to my 2-channel rig, (completely out of the 2-channel signal-path when not in use, & when it *is* in use), i have set-up in my system an audio-only surround-sound processor - the jvc xpa-1010 digital acoustic processor. this unit has in it 20 programs made from acoustically mapping 20 different venues - concert halls, theatres, clubs, churches, outdoor venues. basically, what was done was to point 4 microfones outwards toward the corners, from a centrally-located position in the venue being mapped. so, what's being played-back is the ambient hall info from the particular venue that was being mapped. there are a multitude of adyustments for reverb, delay, the size of the room the system is set-up in, etc. while initial set-up is time-consuming, once it's done, there's not much fiddling inwolwed, except to switch from one venue to another.
imo, this is the *only* effective type of surround set-up for music. everything else is theatrics, w/no meaningful *real* soundstage info. but, i must say, it is now rarely activated, since i've gotten an excellent tubed preamp into my system - plenty of soundstage/hall info yust running the two main channels! ;~) it is nice for some recordings, like live-recordings, & when recordings were made in a real venue, as opposed to a studio. it is also nice, sometimes, for some less-than optimal fm radio broadcasts.
one persons' opinion, doug s.