Why is 2 Channel better than multi-channel?


I hear that the music fidelity of a multi-channel AV Receiver/Integrated amp can never match the sounds produced by a 2 channel system. Can someone clearly explain why this is so?

I'm planning to upgrade my HT system to try and achieve the best of both worlds, I currently have a 3 channel amp driving my SL, SR, C and a 2 channel amp driving my L and R.
I have a Denon 3801 acting as my pre. Is there any Pre/Proc out there that can merge both worlds with out breaking my bank? Looking for recommendations on what my next logical steps should be? Thanks in advance.
springowl
No, a great deal of information is lost - irretrievably - when you mix down to two channels. True multichannel recordings have the ability to capture much more, and preserve more of the original ambience.

Artificially derived channels may very well sound good, but it's not the original.
First I wonder how many of the 2 channel supporters have listened to well recorded multi channel on a well set up high resolution surround system. Those of you old enough may recall the same debates around moving from mono to stereo- not quite a vigorous, not that many people had experienced good sound. Try playing a well recorded surround recording (Diana Krall for one) on something like any good player, Anthem AV20, good amplification and good speakers properly set up. I think you'd be surprised. Don't forget there's a lot of poor quality stereo equipment out there and also good stuff that's poorly set up in bad room that would make most people wonder what all the fuss is about 2 channel. The possiblility of excellent sound in surround is there but just as it takes attention to many details to get stereo working well likewise with surround. Of course we'll still be waiting a while for most of the recording engineers to learn to record properly for it as well. There's lots of poor quality stereo recordings that sound bad on any system and the engineers haven't had 50 years experience with recording for surround like they have with stereo, but they will get there and just like the move from mono to stereo, there will be no looking back. Meanwhile there's no reason not to continue to enjoy good sound in stereo. There's also no reason not to persue the best in surround sound. But there's nothing inherint in the surround technology that will make it a lesser format than stereo- actually there is lots or reason to believe that it can overcome many of the room problems that stereo can't.
To tell the truth I love 1ch over 2ch. I always prefere to buy mono version of a record and might be planning buying mono cartridge when I accumulate large enough mono collection.
Hey guys- Except for one response above, it seems that everyone missed the point of Springowl's question. He's currently using his HT receiver as a pre-amp only, driving 2 and 3 channel amplifiers (separates). His question, I believe, is "can he purchase a HT receiver that will give him as good, or better sound that his current hybrid setup", or should he upgrade to a complete separates setup (high-end preamp with fixed gain HT bypass input, HT receiver for decoding multi-channel mixes, plus separates for amplification be it one, two, three or more channels in the amplifier.

Or, ultrahigh end multi-channel processor (Proceed, Meridian, etc.) instead of the HT receiver and high-end preamp combo. That is his question IMHO.

I don't know the correct answer but I'm about to look at the Proceed AVP-2 processor- preamp combo, which should be upgradeable, in the near future, to digitally decode SACD now that the fire-wire transfer scheme has been agreed to.