stereo amp vs monoblocks, any advantages?

Are there any advantages to using a pair of monoblocs as opposed to a single stereo amp, apart from extra power, that is. If so, what do you gain sonically from this?
Good question.

I'm stretching here a bit , but the main advantage I can see for monoblocks versus say a dual-mono single box design is that you get a dedicated power cord to each side. That would be beneficial I think if the amp draws a lot of current andassuming your power circuits are capable of delivering more current to each this way than otherwise.

There may be some advantages in exposing line level circuitry in the amp to lesser EM fields produced by a single power transformer nearby rather than two as well.

That's all I can think of.
You gain absolute separation between the channels of the amp and much greater flexibility in amp placement. You don't have to worry about such things as weather to biamp horizontally or vertically. You don't necessarily gain extra power, theoretically you can make a stereo amp of any size, but two monos are easier to manage than a stereo one, and , as previously mentioned, what is going on on one channel never affects the other. Monos take more room, 2 power cords and are inevitably more expensive, otherwise they will always be better assuming same quality otherwise.
When you are buying a "Dual Mono" amp on a single chassis check on what they mean, the term is used very loosely, not consistent even with the same company. Some of the Musical Fidelity amps , for example, have two separate transformers, one for each channel, and others have one large for both. Both are called 'Dual Mono". The more parts of the amp that are shared between the channels the more they will interact with each other.
My Stereo IcePower amp has separate compartments for each channel. Each module has own regulated supply. Monoblocks still would be better because they shorten speaker cable.
Thanks guys - I still am not seeing that much of an advantage though. That is, on the flexibility of amp placement (I guess you mean you can have them off to the sides), but you would still be stuck because of the interconnects unless you bought longer ones (a disadvantage). I am new to all this but I wouldn't imagine dedicated power cords would make much of an audible difference, and Kojiki, you might gain in shorter speaker cable but lose in longer interconnects.

Anyway, just playing devils advocate here and am still not seeing much advantage, in fact I would call hauling around two blocks more of a disadvantage, still, I notice most of the serious audiophiles use monoblocks so there must be some real advantage.
Oh, Mapman, the point about the amp drawing and delivering more current - I have read that you should plug all your audio gear into the same circuit if possible, in that case it seems that there would be no benefit as you are still taking current from the same place. As I said, I am a newbee and might be missing something though.
Looking forward to hearing more on this.
Thanks so far guys.
Better isolation between left and right (lower noise potential and less distortion) is probably the most distinct advantage, but even so, either should sound very good and a very discriminating ear might be needed to really hear a difference, all other factors aside.

Two cords might be able to draw power more efficiently than one even on a single circuit, not certain about that though.

I think two circuits can be done in a manner that avoids possible issues like ground loop hum, etc. if needed. A single circuit for very high power amps might be a limiting factor though I believe.
Thomastrouble - with typical 1m interconnect it will shorten each speaker cable by 3' (1m). My 6' speaker cables would become 3' cables without changing interconnects. Twice shorter cable = twice better cable.
My experience with mono amps was with VTL on the tube side and ATI on the solid state side.. I tried the VTL ST-150 on my Maggies then switched to the MB250's. The ATI amps were the 15O WPC models. Those I tried stereo then bridged the two pair for mono operation. In both cases I heard better soundstage depth and separation. The imaging was better defined and just seemed to be more stable.
Thanks guys. Kojiki - are you sure about the twice better cable bit? My dealer told me the best length cable to have was 14 ft, but then again the 14ft length was all he had in stock (hehe). I hate the idea of my gear sitting between my speakers, and this might sound ridiculous but with the great soundstage and imaging I almost perceive the sound coming from the gear when it sits in the middle. I would like to have the gear off to the side with nothing in between the speakers but an imaginary artist /band etc. I posted a while back asking if it was ok to have one long 16ft cable and a 6ft one and everybody wrote in saying this would make no audible difference. Have you heard before that real short cables increase fidelity? On the face of it it to me would seem the shorter the better. As usual, I expect wildly differing opinions but I find it all interesting and I am always learning something, even if it sometimes leaves me even more confused, but the debate is all part of the fun hobby, as far as I am concerned.

Thanks guys.
Shorter cables are generally better.

So is better isolation between components and between components and external EM fields from nearby transformers, etc.

Minimizing these somehow are the factors to consider in a setup for best possible sound.

Also low level signals, like low level phono setups, are more susceptible than higher line level setups. Speaker connections are susceptible as well but to a lesser degree based on my experiences.
Thomastrouble - Different speaker (or IC) lengths are matter for another discussion but it is very difficult to sell them. If you believe that cable is detrimental to sound then effect is proportional to distance (capacitance, inductance, dielectric absorbtion, purity of metal, skin effect smearing etc.).

The only case I know where longer is better (in audio!!!) is digital cable that has optimal length at about 1.5m because if shorter - reflections come too soon (affects the same edge). Transmission line effect does not exist in audio frequencies therefore no reflections.

Dealers often claim that 1m interconnect is better than 0.5m because that's what they have in stock (0.5m is less common) but 0.5m is twice better (almost - connectors also play role).

As for clear space between speakers - why don't you paint stage on the wall and make paper cutouts of your favorite musicians. Change musicians according to record being played. It will improve imaging greatly (he he).
Are there advantages to monoblocks? Maybe. But I would not hesitate to buy a well designed stereo amp because of those theoretical benefits - I own both types. I don't think it is something to worry too much about, if at all, IMHO.
"Are there advantages to monoblocks? Maybe. "

The advantages are real in theory in regards to optimal sound and worth being informed about.

In practice they may or may not matter much from case to case.

And, other factors generally come into play that are more important, like convenience.

Few setups are optimized to the nth degree (well some on this site are perhaps) and still sound great. My system certainly falls into that category.

If I were a vendor selling products or services to others rather than your typical Joe music lover, I would probably pay the nth degree of attention to these things. Otherwise, it really may not matter practically.
Second the "way cool" they,meaning the amps, may not sound
better,but it's like the wire wheels on the Ferrari.
I went from 1 amp to 2 and aside from the obvious power increase and all the benefits from that, I'm now getting better channel separation and imaging. As an unintended byproduct, they also provide nice heat sources in the winter for a north-facing living room as well as the aforementioned "cool" factor as all those tubes just glow their little hearts out... Now that I'm there, I wouldn't have it any other way.
you guys are funny. 1)Less cross talk. 2)no distortion caused by the propagation of the two channels through the system(signal Interferance). 3) indvidual power supplies, which are the most important part of the amp. it's what serves the juice to drive the speakers(cleaner stronger power do to the fact that two channels are not sharing one power supply transformer. especially during the most demanding times.). 4) more powerful, watts per channel. 5) monos tend to be the flag ships with the latest and best available technology. and besides much cooler looking.
O.K. I'll bite and leaving "cool" aside.Kindly explain,if you have one amp that employs two separate amps in the same chassis utlizing individual power supplies,no sharing of transformer,no cross talk and the equivalent power output to both speakers,what,other than shorter speaker cabling are the sonic advantages.
Markwatkiss - no advantage but I can think of one disadvantage: two power cords (good cords might be expensive).
Whenever I lift my 75 lb stereo amp, seems like monoblocks would be pretty nice. They'd probably even sound better to me.
I was channeling Bevis with the "monoblocks are cool" statement but that aside other advantages of monoblocks:

if one goes down for repair you still can listen in mono

or run a center channel with the other

fill up the empty shelves on your audio rack

take up more discretionary income
Markwatkiss - no advantage but I can think of one disadvantage: two power cords (good cords might be expensive).
Nope, unfortunately. My "stereo" requires two separate cords, one for each channel!
I love monos, because I can keep my SCs real short.
This is a very significant advantage, IMO.
This only remains theory because I cannot think of a manufacturer who builds the exact same amp as stereo, dual-mono in a single chassis, and monoblocks. Anytime a manufacturer goes to dual-mono, there will be more power compared to a single chassis. Hence, it is difficult to dissect the contribution of extra power from the benefit of channel separation.

The power supply is the most important part of a component. Being able to duplicate the power will result in a significant improvement. In addition, the ability to separate and truly isolate each chasis will provide benefit. The effect of internal and external vibrations is very real.

This concept holds true for many components. My DAC has separate chasis for each channel (40 lbs each), allowing for a very robust power supply. Having had the DAC power supply increased from one to two transformers per chasis, I can appreciate how important this can be. Likewise, top end preamps separate the power supply not because of interconnect, power, or weight issues, but because of the benefits of isolating different components which can interact in a single box.

Pass Labs has now introduced a lower powered mono-block (the X260.6). Although I have not heard it, I would probably bet that it would sound better than the higher powered, single-chassis X350.5 when used on appropriate speakers.
I'll take a well designed/well built stereo amp over its' poorly designed/poorly designed Chinese (insert your favorite third would country and/or bargain basement manufacturer here) built monoblocks any day.

Two chassis in and of themselves mean nothing.

Should have read "poorly designed/poorly built".

First post was poorly proof read with poor reading skills in poor lighting.
You need monoblocks if the power requirements exceed 1,000 watts per channel, otherwise they are just a luxury.

You can test for crosstalk in a stereo amp by unplugging the left input cable, and listening to the left speaker. It's usually pretty quiet.
I'll have to go with cool also., that just sounds cool. Even cooler when you spell it without the "k".
"I cannot think of a manufacturer who builds the exact same amp as stereo, dual-mono in a single chassis, and monoblocks."

Not listed on the Odyssey website, but I have a Stratos "Dual Mono" that is supposed to be a "two amps in one box" design; it does require two power cords. I have no idea how it compares to the Monoblocks; it would be fun to do a shootout. Any Stratos Monoblock Owners in St. Louis? John
With monos, you can put the amps closer to the speakers and use shorter cables.

I was a mono only macho man for a while, but now perfer a one box solution to KISS. (keep it simple stupid) and after 30+ years of listing, I don't think monos really provide much behond the macho factor) of course maybe I played way too load and now can't notice a few db of cross talk. lol
The main advantage of using mono blocks over stereo amps is that typically, stereo amps use components, chasis, cords, etc. that are shared between channels. With this you get crosstalk. Also, and more importantly, a stereo amp has to drive both speakers, where a mono amp drives only one speaker or better yet, particular individual drivers in a particular speakers, therefore less load on a particular mono amp vs. the stereo amp. The same logic that tells audiophiles to get separates apply with mono amps vs. stereo amps. To get even more crazy, you want each mono amp on a separate power line back to your circuit breaker main panel and on different phases, not the same. That way loading is split on the different phases coming in. Speaker cables have larger current loading and voltages, thereby having larger power loses on the speaker cables. So shorter the cable the better. The mono amps can be placed right next to each speaker and the cables from the amps to the speakers can be really short. This makes a big difference electrically. Longer interconnect cables don't hurt nearly as much, especially balanced. However, if your stereo amp is well designed and stupidly powerful, it really shouldn't matter much. I have found that biamping the speakers (amp for the mid range/highs and another for the bass, for each speaker) make more of a difference than using mono blocks for each speaker vs. stereo amps.

Minorl hits all the important points. On my system, following his monos/short SCs/separate dedicated outlets formula pays big dividends to my system.
Hi Minori - thanks for some brilliant input! I will definitely be using this advice as a reference when I finally get to hooking up monoblocks. I am using a Pass Labs X250.5 with a Parasound JC2 preamp with Magnepan 1.6QRs and the sound is great. I have no audiophile friends to compare systems with so I don't know how great it can be but I am on that mission. I recently bought a pair of Parasound JC1s because they were such a great deal even though there is a small problem with one ( a loose connection somewhere) and am reluctant to hook them up until Parasound gives the amp a look over, this is convenient as I live in San Francisco where Parasound is based. I am hoping I get an increase in sonics afterwards, if not, the experimenting is all part of the fun and I get to see first-hand the benefits.
sometimes you get more space for larger(more) heatsinks as the chassis can now afford them!!!