17 years ago I purchased a JVC RX 815 receiver that had a Dolby Pro Logic processor in it - what we now refer to as the "4.0" version - something about which I knew nothing and cared none at that time. I've used it mostly for music playing into my 2 "front" speakers. I had a Hi-Fi VCR at the time so I hooked that into it and played movies thru my 2 front speakers. I didn't know much or care much about anything else. As I understood it at the time - which is still just as true today as it was back then - that with this version of Dolby Surround Sound the only sounds that come out of the rear speakers are sounds from the fronts played with a delay to produce an echo-type effect. This creates the audible illusion of being inside what you're listening to.
With no rear speakers and very little to apparently gain from them anyway - with the difficulty involved with wiring rear speakers on the other side of the room from my amp - that and I didn't have anything that would actually put out a signal that was surround sound encoded (nit-picking little details) - I never gave it much thought - buying rear speakers.
A few months back I purchased a BluRay player to replace my standard DVD player. It has DTS-HD output capabilities. I think there are quite a few things it can put out - most of which I know little or nothing at all about. NEO6 is in there. I set the thing to downmix output to stereo.
Recently I upgraded my front speakers: Klipsch reference RF-62 (dual 6.5" woofers - horn mid/tweeter) - while I was mentally involved with that I went ahead and bought the RC-52 center and the SW-308 sub now that I have an audio source that actually is encoded in surround sound. It didn't take me long to realize that the center and sub have nothing to add to my music experience - 2-channel CD audio sounds best played with the Dolby processor off (and these Klipsch speakers pump out more than enough bass for me - so using the sub for music is not needed)
I use the center and the sub for movies. I've found that back when I had the Hi-Fi VCR I found myself turning up the volume in places so I could hear what they were saying and then turning it back down when loud action started - but now that I have a center channel I can turn up the volume on that pretty far (+12dB) and hear the voices rather well and not be blown away by the action. I like that. As I understand it - that's not really the function of the center channel - but rather to provide a more uniform sound field to everyone regardless of where they sit (i.e. on the far right or left).
I did change the BluRay to output Surround Sound on one setting and DTS on the other.
I realize that my old receiver has version "4.0" of pro logic - that it only decodes a center and a surround channel and that the 5.1 and DTS encoded movies i'm watching has more information in them than my system can decode and play.
So here's where I am: I have a "4.0" pro logic processor in an old but very good amp. I have an all-Klipsch reference speaker setup with fronts, a center and a sub - no rears. I use just the 2 fronts for music. For movies: I have a Sony BluRay player that is set to output Surround Sound and DTS - I switch on the sub and the surround sound processor on my amp which is set to 3CH mode - WIDE - center volume at +12dB. The center is fairly loud relative to the fronts. I like it that way.
My questions are:
1 - how backwards-compatible is this technology? If I have my BluRay sending out DTS and Surround Sound from movies - and I guess they're all encoded in different ways - i'm renting them from NetFlix - the last one I got said it was DTS-HD sound - is my processor capable of decoding the center channel correctly? My assumption is that it can.
2 - my assumption is that it cannot decode the surround channel it expects correctly because the technology has changed - that information is not the same as what my processor expects - i'd be better off to not even try it. Is this an accurate - guess? Which doesn't matter anyway because I do not have rears - so maybe we won't waste anyone's time on this one.
3 - what can I expect to gain from upgrading to a 5.1 system? My assumption is that I would only gain a slight improvement in my sub - since right now it's just an extension of the fronts - taking the lower frequency sounds from the fronts - but in a 5.1 system I would use the LFE mode of the subwoofer - it would have its own signal. How big of an improvement is that though? Not really worth it is it?
Now if I were planning to add rear speakers to my setup - now that wireless rears are available I just may do that at some point - in that case I really should get a 5.1 or higher amp - right?
My current conclusion is that as long as I do not have rear speakers there's little to gain from upgrading to 5.1 but if I ever do decide to get rears I absolutely have to upgrade to 5.1 if I want the rears to actually add value to my movie experience.