Well, all things asside, a 2 channel system doesn't really need distance parameter settings, and auto sound leveling, and such, IMO. I mean, it's irrelevent if the system knows how far you sit from your speakers, as the sound gets there when it gets there, so to speak. And you can EASILY balance the sound between 2 measly speakers, and tell where the balance is set between there (Pick any recording you know, where the vocals are dead center, and adjust your balance levels accordingly!)
There again, in trying to creat the best possible performing 2 channel and multi-channel audio system possible, there's many issues to consider and deal with here, in a perfect world. However, straight up, more pure pre-amp and amp combo's, mixed with superb sources (like excellent digital players, analog, tuner, etc) are often the prefered high purity path to great 2 channel sound - nothing else considered. If 2 channel is all you're doing, ideally, and you have a SUPERBLY CONSTRUCTED ACOUSTIC SPACE and setup, then you can really (at this stage of the game) get better audio 2 channel performance (at the very least), with a world class 2 channel preamp and amp combo for 2 channel dubties. Adding some of the better (limited, indeed) multichannel dedicated preamps out there, and multiple amps and speaker combo's, you can then achieve more state of the art "sound quality", IMO, for multi-channel music, and such, yes.(not necessarily DD/DTS multi, as that sounds better usually processed through an AV pre/pro, for various reasons I've found).Now that's an ideal scenario, again, all things perfectly setup, perfect room (almost impossible to do in a typical living environment), and lots of knowledge about tweaking and dialing in a system - 2 channel or otherwise.
Now, here are some of the major drawbacks and issues to "audio-perfection", if you will, in that most people have FAR from perfect acoustic spaces, if not down right severely acoustically problematic spaces and poorly engineered setups! In this case, if you could first make a good foundation for 2 channel setup, by placing listening seat(s) and speakers fundamentally correct(flat response, good imaging, solid soundstage, proper tonality, clarity, focus, and dynamics, etc), it would then possibly better achieve what would be, again, a more pure fidelity. Of course, you need the best quality gear (I like active, high efficiency, high end designs for this endevor - but you get the point). But this is the ideal! And in most people's case, even if they are proficient at setting up a couple of speakers and a chair in a system, they would still likely have all the other acoustical concerns to adress, otherwise you can garantee they will be compromising their otherwise possibly superb audio system.
Now as of the last several years, there have been good 2 channel products out on the market to help deal with some of the basic acoustic issues in systems, like TACT and Rives PARC, etc, that help the fundamental response of an audio system.- furthering what's practical and capable from an audio system. The products like the Rives PARC, alone, have helped people "EQ" the nasties out of their systems in terms of bass response, which helped greatly in terms of fidelity improvement and accuracy, considering the acoustically challenged spaces most everyone deals with.This has helped bring higher fidelity even further in typical domestic spaces.
Enter AV Pre/pro's!...
...Some of the better technology in today's processors allows for even futher refinement of sound processing, via the likes of "Audyssey DSP room correction" What even professional audio/video reviewers have found, is that the acoustical benefits which these such technologies offer possibly outweigh alot of the "refinement benefits" that the otherwise "higher fidelity" gear offers, or even some of the best, most higly refined audio equipment in typical acoustic environements is capable of by itself!
What todays AV pre/pro's are starting to do is to do what only thousands and thousands of dollars in room construction techniques and acoustial treatments are capable of doing, in furthering the potential sound quality from a system!! Something like the Audyssey, it seams is making even modest more entry level type systems perform more like higher fidelity systems (and better in some regards). You then take some of the better sources, associated equipment, speakers and cables, etc, and you put em together with a system that's using this technology, and you have some prettty impressive sonic potential!
Traditionally, yes, a dedicated separates based 2 channel system has been the potentially superior sonic path, over using an AV pre/pro (or av receiver as a preamp). But now there's other variables in the game! I think some of the better pre's that are starting to incorporate this kind of room correction technology are making higher fidelity even more achievable with normal means, in more applications and setups. Wether a dediated 2 channel or mulit-channel system, the overall sound quality being available through a well planned system using something like "The Audyssey", can be simply spectacular! - and achieve what was otherwise not possible sonically in certain aspects, previously practical to attain.
So, what I'm saying is, if I were trying to get the best possible sound from a 2 channel system today, in a typical challenging acoustical environement, I would either be using higher end audiophile gear, and AT LEAST be incorporating something like a Rives PARC to EQ the system. If I was using more mid-fi gear, I would be looking to use a digital AV pre/pro with digital connections, and using a pre/pro with something like the Audyssey room correction processing! (proper setup fundamental procedures and foundation considered for best possible results - i.e, no holes in the response, and limited acousitcal liabilities). Otherwise, I could also possibly use higher end gear, and still incorporate the digital pre/pro mentioned, and get different benefits, and similar results all around.
Another possible scenario, is to do what many are doing here - which is loop in an AV pre/pro into a 2 channel system, maximizing some of the fundamental purity from the 2 channel sources, and keeping the benefits of the AV pre/pro and current processing for multi-channel music, movies, etc. What I find here is that you still very much need to maximize your 2 channel setup, and deal with proper acoustical integration and room setup, for best possible sound, WITHOUT DSP room processing and EQ! (for the 2 channel system, at least).
An ideal world here would be that some of the better high end audio manufacturers would start to incorporate more of the kind of technology that Audyssey is offering into their products! I'd like to see companies like Krell, Audio Research, Meridian, Theta, Pass Labs, whatever, etc, that are making 2 channel and multichannel preamps alike, start to offer products that incorporate some of this current DSP room correction technology, personally. I think what would then be possible, would an ultimate sonic experience from a typical system, yes!
Right now, there's compromises and trade-offs. On the one hand, my experience as an audiophile, enthusiest, and professional custom guy, is that experience has shown me that traditional 2 channel systems, made up of higher end gear, offers better potential sonic capabilities over your mid-fi digital pre's and receivers, and such - But that's in an ideal setup. I know what acoustics in customers house can do to wreak havok on the sound of a system!
In my world, with the right time and a budget, I know I can build a world class acoustical environment, properly setup up high end, quality audio gear, dial it all in, and achieve nothing short of world class results! But when those ambitions and applications aren't available, you start to deal with some serious obstacles acoustically, and some compromises to the sound. Now-a-day's, some of this better digital DSP tech is offering some fixes to get over some hurdles, and still allow you to achieve some pretty stellar sonic results, from even more modest systems than ever before! And, for the average consumer or enthusiest, who want to put the highes possible performance system together, with limited means and options, I think what's available using an AV pre/pro and higher end sources and speakers, equipment, powerconditioning, tweaks, and such, is the way to go. You can then get the best possible sound from all sources and applications - that mainly because the sound of the room, the acoustics, and all the necessary tweaks, make up at least 50% (if not more, depending) of the overall soundquality that you here in a given system! And the Audyssey can help perfect about 80% or more of the acoustical challenges that are most often pressent in a room/system.
I won't get into what all exactly something like the Audyssey is doing to help benefit the sound (you all can research that on your own). But I will say this IS the dirrection that we need to be going as an industry, and incorporating this tech into more and more products, high end or otherwise.
I would say then that, down the line, with proper due attention, that an ultra high end performing system could be achieved with limited means, by using a either high-end sources or dedicated high-end 2 channel preamps, multi-channel preamp,etc, which some how incorporates Room DSP processing! Right now, that technology, and those affordable benefits are being offered in only limited mid-fi products, unfortunatly (or fortunately, however you look at it). So, there are compromises, and then benefits also. For a completely digital AV system pressently, the best route is to do all your processing in the digital relm, for both 2 ch and multi, movies, etc, via a good DSP EQ'd AV pre/pro and amp combo! - and all connections mostly digital ones.
With all the benefits being offered in mult-channel AV systems these days, via the kind of technological advances we are implementing these days in pre/pro's and receivers, all the necessary acoustical corrections, delay settings, phase controls, level settings, etc, yes, can all be quickly and easily processed for speed and convenience.
This makes it possible for more and more people to have great results from their systems, in a timely easy fashion. In short, these systems are effective, and sound good when done right. Technology is making things better and easier.