Why 7.1 Surround Sound is Overkill For Most Homes

RX8 writes "Home Theater expert Mark Fleischmann explains why you should not fall for the 7.1 hype and why 5.1 surround sound is adequate for most homes. From the article: 'With the marketing of 6.1 and 7.1 surround, the industry has decisively outwitted itself. It has convinced many consumers to buy new receivers and more speakers. But it has also undermined the 5.1-channel standard, which is more appropriate for the home, slowing the acceptance of surround sound in general.'"

Comments

2 ears, 2 speakers

[deprecated]

That is the Law. Are we not men?

Re:2 ears, 2 speakers

[afaik_ianal]

True - and there's a pretty cool demo of what you can do with two speakers (well, headphones) here: http://www.dolby.com/consumer/technology/headphone .html.

Of course this is a good example of why multiple speakers is a GoodThing(tm). The human ear is pretty good at telling where a sound came from (based on echos, etc). Doing what they do in the demo above would be pretty tricky if your speakers weren't stuck to the side of your head.

Re:2 ears, 2 speakers

[ajs318]

Indeed. I for one would prefer to have two decent speakers driven by amps with a frequency range of 4Hz-20kHz +/-1dB at 1%THD, than to have any number of crappy speakers driven by amps with a frequency response of 100Hz-10kHz +/-6dB at 10%THD.

Informal experiments with my neighbours would seem to suggest that when listening to music outdoors, THD is more noticeable than absolute volume: you can play it as loud as you like as long as it's coming through crystal clear, but the minute you introduce a little distortion you will be asked to turn it down.

Re:2 ears, 2 speakers

[iezhy]

there is difference - 7.1 receivers in same price segment will perform worse (in terms of sound quality) than 5.1, not even speaking about stereo (stereo amplifiers usually can be compared to receivers that have 2x price).
This is because price per channel - the more channels and various decoder electronics you put, the less buget you have for sound quality (cheaper tranistors, capacitors, poweer supply, etc.)

Re:2 ears, 2 speakers

[semiotec]

stereo? Bah! Real men listen in mono! I am currently perfercting a technique where I use my tongue to sense the vibration in the air. Hmm... taste that Britney Spears...

Re:2 ears, 2 speakers

[Sycraft-fu]

Also, for as cool as HRTF can sound, the illusion breaks the moment you move your head. We move our heads all the time, and our brain takes this in to account with our audio perception. Ot expects the sound will change in a certian way as our head moves. We actually uncounciously use this to help us localise sounds. Well with headphones, the entire soundfield rotates with you. It's not natural, and you notice it.

That doesn't mean it's useless, however it's still not as realistic as multiple speakers.

Re:2 ears, 2 speakers

[scrm]

This demo of 3D sound out of two speakers still blows me away: http://www.holophonic.ch/archivio/testaudio/Cereni %20-%20Holophonic.mp3

Re:2 ears, 2 speakers

[Impy the Impiuos Imp]

Next thing you know, they'll be telling us "5 blade" razors are stupid, too!

Re:2 ears, 2 speakers

[ajs318]

Because half the time, it's not the speakers that are the crappy bit, but the power supply for the amplifier.

After thirty years or so, we've got good enough at making op-amps with a decent gain-bandwidth product. Any amplifier you can buy will amplify, and will do so closely enough to ideally over a band easily broad enough for the human ear. That's not the real challenge anymore. The loudspeaker is important, but there have been improvements in both manufacturing precision and the understanding of the underlying physics. Even cheap speakers are reasonable as compared to what people used to put up with in the past.

Where it's all gone Pete Tong is in the power supply serving that amplifier.

The proper way to construct a multiple-channel amplifier is to have a very low pass filter -- series choke and parallel capacitor -- between the PSU proper and each of the individual power amp stages. This presupposes "star wiring": the current drawn by one power stage should not have to pass through a conductor which is also serving another power stage. Otherwise, you can get crosstalk induced from one channel to another. Each power amp stage needs a big hefty capacitor to supply the energy to handle loud passages between peaks of the mains, with a smaller ceramic -- not polyester -- capacitor across it to shunt out high frequency noise. {A separate PSU per power stage would be ideal; any crosstalk would have to make it all the way to the mains wiring, whose internal impedance is closer to a short circuit than can easily be made in the laboratory.}

Cheap, crappy multi-channel amps have all manner of nasties, like power rails that run across from one stage to another and under-rated capacitors that can't cut the mustard. In fact, the transformers used are frequently under-rated for the application: if you run the amp continuously just at the onset of distortion, the power transformer's thermal fuse will fail. That, by the way, is part of the reason why audio amplifiers generally use transformer power supplies. Part is that you can get a very nasty crosstalk between audio and the near-ultrasound at which SMPSUs tend to run, causing sounds to be heard that were not present in the original; but the other part is that big, chunky transformers heat up slowly and are generally more tolerant of abuse.

The reason why this situation has arisen is that manufacturers are designing down to a price point, and not up to a standard. And as long as there are more than a certain critical mass of gullible idiots out there who will pay good money for any old shite as long as it's shiny shite, I don't see any way out of the situation without some form of government intervention.

Re:2 ears, 2 speakers

[Golias]

Prior to 5.1 movies, that was always the argument against "quadrophonic" surround systems, too.

The argument was, if you pass on surround, you were giving up a tiny bit of ambiance imaging, but you had twice as much money to spend on good stereo speakers, and could buy a much better amp.

It's still true. For what I spent on my home theater's audio set-up, I could build a downright orgasmic stereo listening room... but my desire to watch movies in 5.1 trumps my craving for maximizing my hi-fi ! for $.

Besides, Hi-Fi ain't what it used to be... it's better and cheaper. Thanks to the computer revolution of the 80s and 90s pushing down the cost of transistors, I can buy a $100 stereo amplifier which kicks ass all over stereo amps which cost twenty times as much back in the 70s. My $500 5.1 amp does a fine job at faithfully reproducing music.

Quality speakers have come down, too. Again, thank computers. Home-brew acoustic design software de-mystified the art of building speakers a little bit, and launched a new wave of small-name designers.

My B&W speakers (Bowers & Wilkins, a British speaker-builder) sound downright glorious, and even with the center channel, they cost less than the kit my father once used to build his own I.M. Freed subwoofer/satelite combo. Plus, he had to deal with an expensive cross-over amp, while my powered sub enjoys the discrete 5.1 subwoofer signal with far less hassle.

stereo anyone

[cobbaut]

Most non-tech people i know already have to make an effort to place two stereo speakers correctly in their livingroom,
placing six or eight is often too much trouble.

Re:stereo anyone

[DrXym]

Most non-tech people i know already have to make an effort to place two stereo speakers correctly in their livingroom, placing six or eight is often too much trouble.

Replace often with always. I can understand how some audiophile might appreciate the ability to fine tune dozens or hundreds of parameters such as speaker positions, direction, tilt, balance, cabling etc. With such people the quest for perfection is neverending and sometimes exceeds common sense. I suspect that most other people would be happy with a sub $6000 5:1 system from their local electrical outlet or nothing at all.

I myself like watching films on my big widescreen TV but I haven't had a strong urge to hook it up to a sound system. The speakers do the job adequately for my needs. Just the thought of extra cabling, power plugs, amps (occupying space in my cabinet) and remotes puts me off. The same goes for my PC. I play lots of FPS games, but I make do with a pair of stereo speakers and a subwoofer, both of which were bundled with my last PC. It would be nice to hear sounds from behind but IMHO not worth the hassle of all that extra gear.

Re:stereo anyone

[jiushao]

I suspect that most other people would be happy with a sub $6000 5:1 system from their local electrical outlet or nothing at all.

Do you see what you are saying here? A $6000 system, do you want people to live like animals? You are what is wrong with the world today, denying the common folk the very basics of civilized living.

Re:stereo anyone

[ThePhilips]

From what you are saying, one might think placing too is easy. But you are right: proper 5.1 system take quite much space. I would say the same amount as good stereo. And I yet to rent a flat which would allow me to put proper stereo inside. In U.S., in private houses it's quite possible. Over here in Europe, flats are terribly small and not quitable for any kind of proper stereo.

As to 2/2.1/5.1/7.1. My friend at one time bought "expensive" Altec Lancing 5.1 system (~$250). When we compared it to sound of my home stereo (~$1.5k), guess what my friend did? He sent the 5.1 back to shop. Next week-end he came over to me and said: "Lead me to a proper shop". He purchased on my recommendation Harman system (Harman/Kardon + JBL) and never looked back.

And even now, my cheap mini system from Yamaha (PianoCraft 400, upgraded cables and bit tuned speakers, $400 + upgrades $150) outperforms 5.1 system of any of my friends. At least that what _they_ say ;-)

I can say that definitely there is progress in quality of 5.1 systems. But at the same time stereo goes on too. The main problem of most 5.1 systems (even if you managed to position it well) is poor stereo quality. Music is still stereo and music is what most often played on any system ;-)

Sidenote. Many DVDs come with crapy stereo sound track. Most of my friends with stereos bought some kind of 5.1 systems just for sake of watching DVDs. IOW, popularity of 5.1 can be bit inflated.

Re:stereo anyone

[cheezit]

That may be because you are listening at higher levels than you would without headphones. There are two things that might drive you in that direction:
1. Fletcher-Munson curve - music sounds better loud, assuming no distortion
2. Isolation - headphones block out external sounds, allowing the ear to pick up details. The louder it is, the better the isolation, so the better the sound.

Watch your hearing very carefully. Once you lose it, it ain't coming back. Pete Townshend has attributed his hearing loss not to loud amps but to coming home after concerts, drunk, and playing through headphones all night while his wife and kids were sleeping.

Unless you're a real videophile

[Alioth]

Unless you're a real videophile, you're probably better off just buying two really nice speakers instead of 7 average ones. Not to mention the rats nest of cables 7 will result in.

Why 5.1 and not 2?

[Vo0k]

Well, movies, music, such stuff where quality matters, if you're a connesseur you may want 5.1 or even 7.1. But 5.1 may mean difference between being alive and dead, and you NEED it in certain case.
Friend's tale. He's the 1337, I'm just a n00b so it doesn't matter in my case. UT deathmatch. He bought his new 5.1 and configured it correctly. Some tunnel deep underground. And then he hears, left-behind, the sound of a Ripper, that deadly spinning disk that upon hitting your neck cuts your head off, granting the opponent an instant frag and counting as headshot. "Duck" and the ripper zooms over his head. Fast turn and a rocket into the enemy's face. One frag less for the opponent, one more for him, one 1337 tale more to tell, one more deathmatch won in total... Thanks to 5.1.

go Low Budget

[anagama]

When I was in school, I set up some ambience speakers "left minus right". Very easy, just connect the front two speakers like normal. Then connect a second set of speakers to sides and behind the listening area -- except only connect the positive terminals to the amp, and then bridge the negative terminals between the speakers. I about jumped out of my skin the first time I listened to some old "Dead Can Dance" album and it sounded like the shaman's rattle was right behind me. Hmmmm, maybe I'll set that up again -- except the extra wires are a real drag. Oh, Roger Water's "the pros and cons of hitchhiking" was great on this setup too.

Re:go Low Budget

[Sycraft-fu]

That's Dolby Pro Logic, in essence. It's a 4 channel matrix of two channel sound. While the implementation is a little more complex in reality, the basis is this: Every thing that is either left or right is rent to the respective channel. Everything that is left + right is sent ot the centre channel. Everything that is left - right (or out of phase in other words) is sent to the surround channel which is two speakers in the back. It allows for the reasonable encoding of surround information in a stereo track, that also results in a good sounding stereo track.

If you like that, and have more money, you might want to check out a Prologic II decoder, which most surround recievers are these days. It's a more advanced system and does a better job at upmixing to 6 channels.

Re:3D positional audio

[Rothron the Wise]

Games need hardware that do 3D positional audio because the scene is unpredictable. It needs to be calculated on the fly. Any 3D positional effects in a movie would be static, added when
the movie is mixed, or else you'd have to include all the seperate audio tracks.

Such effects are difficult to pull off in a large area like a movie theatre, and would be
very dependent on the speaker configuration, which is probably why you don't see a lot of this.

Amount of content = very little

[TheGSRGuy]

There's practically no content encoded in 6.1 or 7.1. And the stuff that is...well, most people probably can't tell a big difference. Example: Castaway is encoded as a DTS-ES disc, which is VERY rare. I'll tell you, I've watched the movie twice now: once in regular DTS and the other in DTS-ES, and I was hard-pressed to tell a difference. The latest DVD release of Top Gun actually has DTS Discrete encoding. Again, I really had to concentrate to hear that extra channel versus my older 5.1-encoded copy.

I did like one point: why would you want more rear speakers than front? The center speaker produces the majority of dialogue in a movie, not the rear channels.

I have a 6.1 system, yes. I didn't intentionally do this. I watch non-digital TV with PLIIx decoding, and watch my movies with Dolby Digital EX. Frankly, I can't tell the difference. That "center surround" speaker is more for bragging rights than anything else.

So just to reiterate, I won't call 6.1 and 7.1 totally worthless, but yes, it is overkill. Movie experiences at home won't suddenly be way better. And the complete lack of 6.1 & 7.1 content makes the format rather pointless.

So many ways to be wrong

[JanneM]

There's so many ways to make mistakes when setting up sound - and with more stuff, more choices, more tweaking possible, all but the most dedicated sound geeks are simply getting more ways to mess it all up.

The reality is that for most people, setting up two good speakers, or maybe two speakers and a subwoofer in the center, is going to give them the best sound. Add various little satellite speakers and stuff that is really dependent on the room layout, the prescence of sound reflecting and absorbing materials (table surfaces, soft couches etc.), the unpredictability of where people are sitting and chances are they will end up with a soundscape that sounds decidedly worse than they had with a simple 2 speaker or 2+1 speaker setup.

It's like having high-end Öhlins shock absorbers on your bike. For the riders that _are_ (not just think they are) knowledgeable, interested, and ready to spend a week tinkering, they will give superior performance to the factory default shocks. For the rest of us, they're just an expensive invitation to utterly screw up the bike handling beyond all help.

Re:So many ways to be wrong

[JanneM]

I'm having trouble figuring out why so many people in this thread seem to fail to understand this. Two speakers is not going to give you the best sound from six separate channels. It just isn't. Five full-range speakers or five satellites and a sub is going to give you the best sound from six separate channels. I mean, it's just common sense, isn't it?

You misunderstand my post a bit.

What I'm saying is that taking those 5+1 speakers and placing them badly, not connecting all speakers the same way, not mixing it approximately right and so on, is actually going to end up sounding worse in practice than a technically less good two or 2+1 speaker setup. Not because it actually _is_ worse (as you say, you have the sound info), but because you can mess up the installation in so many more ways - and most people will mess it up.

That's what I tried to exemplify with the shock absorber; though it may not be all that illuminating unless you own a bike, I guess.

It's all canned sound

[Quirk]

There was a famous american conductor active around the mid part of the last century who was widely known for his refusal to record. He characterized recorded music as pancaked sound. Although this was in the vinly era his criticism still holds. More speakers, even properly spaced, don't lend a benefical comparison of recorded music to a performance.

You can listen to any recording of say the Kronos Quartet, but no matter how well the recording tech is matched to the medium the sound is flat compared to hearing the quartet play live.

I sometimes prefer listening to something from a seminal jazz album like Bitches Brew on a turn table because the vynil has a warmer sound to my ears.

You can add all the speakers and present day tech you want it's still pancaked sound.

Re:It's all canned sound

[Skater]

Yes, but it's not really practical to drag Queensryche over to my house every time I want to hear "One More Time".

Summarized for Your Convenience

[thib_gc]

Summarized for Your Convenience: "Why 7.1 Surround Sound is Overkill For Most Homes: because seven plus one is eight, which is a lot." Thib ;-)

Equipment vs. Media

[mauthbaux]

I personally have a decent 5.1 surround system. It's far from the top end of things, but noticeably better than most of the cheap systems you see for sale at Wal-Mart.

From the variety of movies that I've watched on it, my big complaint lies with the audio encoding of the movies themselves rather than with the equipment it's playing on. I have a few hundred DVDs, and there's only a handful of them where it seems that any real effort was put into the channeling of the audio. The Superbit version of the Fifth Element comes to mind as a movie that simply sounds incredible with the surround. Most of the rest of them fall short, even ones with dts.

I have a suspicion that the dts tracks on some of them were just copies of the Dolby (or even Stereo) tracks that had just been resampled at a higher bitrate. It would be like using a casette to record a song from a radio broadcast and then encoding it into a 128kHz mp3. It's still not going to sound as good as the original (The original CD... not the radio recording).

Anyway, perhaps I'm wrong but, it seems like the shortcomings in my sound system (and many others as well) is not so much the equipment, but the quality of the media being played. Anyone else seen a difference between DVD distributions of movies? Or perhaps have a preferrence in the companies you buy your DVDs from?

Re:The Real Sound

[Hast]

http://www.theonion.com/content/node/33930

Thread over.

2d video = stereo

[tobes]

I find it distracting to hear sounds behind me (any form of surround) when the picture is in a two dimensional field in front of me. Especially when the effects tend to be breaking glass or bullets pinging off things.

Re:An experiment

[patrixx]

First of all, light and sound are *very* different phenomenons. Light is very weird, sometimes behaving like particles and sometimes like waves, depending on what you expect from the experiment. Einstien et al knows more about this.

However you analogy in this case is correct, but not your conclusion.

Soundwaves can also can be compared with ripples and waves on a liquid surface. If you throw a few small stones and big rocks into a swinning pool, the waves and ripples from the impacts will interfere with each other and bounce off of the walls and corners of the pool. This is comparable to the situation in a room with speakers. The big rocks are the bass speakers, and the small stones are mids and highs.

The smaller waves from the higs and mids ride "on top of" the bigger bass waves mostly unaffected. But charateristics in the room makes the big waves move irregular and sometimes "cancel" each other when bouncing in the corners. This affects the ripples riding on them and creates mostly "temporal" errors - A high or mid frequency sound does not reach your ears at the exact right time, which is crucial for the surround effect.

Because of this it is better to transform the sound signal as close as possible to the place where it should be in the virtual sound space, not letting the "chaotic" wave situation in the room affect it. And this in turn, concludes that more speakers are preferable.

This is all very theoretical, and in a normal living room 5.1 is plenty I would say. In larger rooms however many speakers can be critical to create a good virtual sound space.

If waves did not interfere with each other this way, two speakers would be enough to create perfect 360 dgr surround sound anywhere. This is known as "virtual surround" and works flawlessly in a echo free room. In a real room the problems mentioned above makes it less effective.

Regards /Patrix

Ok this guy is doing more than just a little BSing

[Sycraft-fu]

This whole "clipping is a fact of life except in expensive systems". No, not so much actually. I'd be really supprised if most good reciever/speaker combos ever clipped. It's not hard to build an amp that has plenty of power for home theatre, espically when you are talking the distances at which the speakers will be placed. Generally people aren't going to be running them at a whole lot more than a couple watts RMS.

The thing is that recievers are all transistor amps, and clipping is really noticable on transistors. Transistors are essentally completely linear up to a point, then they just stop hard and don't put out any more power. It isn't quite as harsh as digital clipping, but close. It's not smooth like tube clipping where the tube slowly enters a non-linear zone.

Also, more channels wouldn't give a reciever any more reason to clip. Each channel is a seperate amp. What matters in regards to clipping is the amount of power going in to a single channel. If it's more than the channel can handle, you clip, if not, you don't. What's happening on the other channels isn't relivant.

He's also wrong that there's no reason to want more speakers just because there's no seperate encoding for them. If that were the case, why the hell do theatres have more than 5 speakers? Well, because the sound would suck. You have people all spread out, you need surround speakers all along the walls to get a good, diffuse surround field that's pleasant for all of them.

It's actually the same reason behind a centre channel. In theory on a good setup, such a thing sould be unnecessary. Indeed you find this is the case, if you have two quality speakers that are focused on a listener, they can generate a perfectly centred sound by playing in unison. No need for a speaker there. However, that relies on a very small sweet spot. If people are spread out, the illusion breaks. So, we just put a speaker in the dead centre, and send the sound there. It makes the sound seem to come from the middle of the screen, regardless of your angle to it.

The real reason not to get 7.1 in most cases is you are wasting money because your listening area is too small to really benefit from more speakers. However, it's not going to make your reciever clip or anything, unless you've got a seriously screwed up reciever.

Re:Watch LOTR ROTK

[iainl]

I can't tell the difference.

But then, I've got my 5.1 set up correctly and I sit in the right place. In the same way, if you're in the sweet spot, then the centre speaker isn't needed either.

6.1/7.1 is a really useful invention for cinemas in particular, as it allows you a much larger range to sit in where the surround still 'works' correctly. Which is the whole article condensed, really. If you've got your speakers set up right, then adding an extra one or two directly behind you doesn't really add anything. If you've got multiple sofas in your room, then the people sitting to one side of the TV will get a better surround effect with that centre-rear channel.

So while I'd definitely agree with the premise that rubbishing the idea for home presentation is wrong, it _is_ worth considering on an individual basis whether it is worth spending money adding the extra channel to an existing setup.

I bought 7.1

[Mark Hood]

And here's why.

I had a TV with built in 5.1 surround (including some lousy satellite speakers but no sub), but it didn't support DTS, and without a receiver of some sort I couldn't add additional inputs.

So I decided to buy a 5.1 receiver and speakers.

At the store, they had a 7.1 receiver which I'd read reviews of, and they said sounds like it cost well over £1000 but was only £300. They had it reduced to £250.

So I bought it. And a set of 7.1 speakers (the same price as an inferior 5.1 set) in which the rear 4 can be spliced together as pairs - reducing it to 5.1).

Since I have a small room, and no 7.1 source, I've left it as a 5.1 system, but it's nice to know if I ever get a larger room I can split up the rear speakers and properly fill in the rear channels.

That said, I agree wholeheartedly that I'd not swap a 5.1 for a 7.1 system, if it cost more. I went from a sort of 5.1 to a real 5.1 for a sum I was happy to pay - and can now upgrade to 7.1 should it prove useful for the cost of two speaker stands.

Mark

Re:Watch LOTR ROTK

[x-router]

Saying that you have your 5.1 setup correctly seems to suggest you only have 5.1. Have you actually tried a 7.1 setup? It does make a difference.

I agree that anything setup badly will not make any difference and in the case of 7.1 it would be a mess. But if you have gone 7.1 then I assume they have paid good money for something to drive it and some good kit to host it. If you have paid less than 5k for your setup then it's probably pointless to go 7.1.

Just because your average Jo doesn't need 7.1 tho doesn't make it any less good. TFA misrepresents the benefit on the basis that it doesn't make much difference to a non cinema environment...This is not true.

Re:Ok this guy is doing more than just a little BS

[The Clockwork Troll]

Also, more channels wouldn't give a reciever any more reason to clip. Each channel is a seperate amp.

A receiver's amplified channels still share a single power supply. This is kind of the defining trait of a receiver, actually (and, along with pre-amp stage purity, the source of all the receiver vs. separates debates of the ages). If the power supply (with support from capacitors) cannot maintain rail voltage for the load across the channels at a given instant, all channels are generally going to clip, go into "protection" mode, etc.

Re:An experiment

[pAnkRat]

"realnowhereman" (263389) in reply to "BadAnalogyGuy" (945258)
> None of what you say make any sense

Do you know who you are replying to?
BadAnalogyGuy is not just a name, it's a way of life.

Center Channel

[D.A. Zollinger]

Actually the center channel has a specific and unique use. The majority (like 90%) of the dialogue comes from the center channel. This means two things; first your center channel speaker must be the best speaker in your setup so that you can hear the dialogue clearly, and second, this allows you to isolate the dialogue and alter the volume for it separately from the rest of the content.

If you have ever played a surround sound DVD on a stereo setup, you would know what I am talking about almost immediately. The dialogue has been mixed with the other sounds and forced out of two speakers, and the dialogue has to compete with all of the other sounds being generated. This makes for unclear dialogue, or dialogue that changes from being too soft or too loud in comparison with the rest of the movie soundtrack. With a multi-speaker setup, you can increase the output of the center channel for added dialogue clarity without increasing the overall volume of the performance.

For fun, next time you go to an audio-visual store, turn off the center channel and watch everyone wonder in amazement how they can hear all of the sound effects of the movie, but no sound comes out when people move their lips. This is especially fun in places like Best Buy where the "audio experts" only comprehension of audio systems is that they are not paid on commission.

I don't know about you but...

[brunes69]

... I find it hard to conceentrate on the TV while moving my head all around the room.

Re:Ok this guy is doing more than just a little BS

[Shawn Parr]

Also, more channels wouldn't give a reciever any more reason to clip. Each channel is a seperate amp. What matters in regards to clipping is the amount of power going in to a single channel. If it's more than the channel can handle, you clip, if not, you don't. What's happening on the other channels isn't relivant.

Actually cheap receivers have very cheap and limited power supplies. The more channels you drive the less power that is available to all of them. As such if you hit a loud passage with sound in more than one or two channels there will not be enough available power and the volume at which clipping occurs drops. If there is a current supply of 2A, and two channels each require .7A at the peak level you will not clip. If suddenly that same receiver needs to supply .7A to 5 channels you exceed the 2A supply and you will peak, on all channels, not just the 3 that didn't have high output before.

However, it's not going to make your reciever clip or anything, unless you've got a seriously screwed up reciever.

The real issue is that most receivers are seriously screwed up due to cost concerns in manufacturing. Any receiver bought outside of a hifi store, or from an online only hifi manufacturer are going to have inflated specs. Many receiver specs show the power rating for only one channel driven. Some show it for two channels driven. Very few companies show the honest rating of how much power is available per channel with all channels driven (Harman Kardon, Rotel, etc.) and those tend to cost more than your average Kenwood or RCA that most consumers see at your Best Buy type of store, and let's face it, modern consumers no longer understand the difference between price and value. Just because it is cheaper doesn't make it a better value, often the opposite is true.

He's also wrong that there's no reason to want more speakers just because there's no seperate encoding for them. If that were the case, why the hell do theatres have more than 5 speakers? Well, because the sound would suck. You have people all spread out, you need surround speakers all along the walls to get a good, diffuse surround field that's pleasant for all of them.

This is very insightful if your viewing area in your home is the size of a theatre. You do realize that in most cinemas that the speakers all along the walls all carry the exact same signal? As you said it is so that the sound field is diffuse for a large audience. This has absolutely no bearing on most home systems. 2 surrounds can easily provide this sound field, especially if the consumer has the skill, or the interest to learn, to set them up properly.