Why does bi-amping speakers sound better?

Curious why it sounds better to bi amp speakers vs just running them off one amp?

i am trying to figure out which amp to buy, I am on the fence with bi amp or not.  Speakers are the old infinity kappa 8.1's.  Several years ago when I was married I bi amped my speakers so each speaker was seeing two channels from a parasound hca1500, I think that's the model.... 200w x 2 going to each speaker.  I also tried a single amp powering both speakers so each speaker was seeing 200w x 1.  

is it that I simply doubled the power that resulted in better sound, mostly noticed the low end of the speakers was tighter, more powerful etc.... and obviously I could also play louder.  

Or is is there something about letting one amp not work as hard due to only running high frequencies while the other amp gets to just work on the low end.  

I am 90% sure which brand of amp I want to get, just trying to figure out if I should bi amp or not.

as a example should I go with

two 2 channel amps at 400w x 2 so each speaker would get 400x2

or should I go with a single 800w stereo amp so each speaker sees the same 800w, just with one channel of a amp

A number of people, including Richard Vandersteen, think most (maybe all?) of the advantages you heard come from the fact that bi-amping inherently bi-wires. 
Depending which directions the channels are sent cancelling out more crosstalk between a pair of channels. Not having to push a single amp into distortion is one other reason things will sound better, two amps may have better control over the speakers if just one wasn’t quite inadequate.

Variable gains are helpful here, thats one thing I will consider if seeking a second amp. 
the main effect is that each amp will drive a smaller load, so the incidence of clipping is reduced

for a manf., the amp can be tuned to the needs for each type of driver
I think current bi-amp configuration leans more toward horizontal than vertical. That is using one amp per channel (monoblocks), instead of splitting the upper and lower frequencies.
As randy said, it allows an amp to drive less of a load-which would be very advantageous when connected to inefficient speakers.
Using two monoblocks also let you place the amps close to the speakers, so you don't need long runs.
Dual amping also gives the option of running an amp that fairs better with bass on the lower posts. My bryston 3B put a death grip on bass while it wasnt that nice on highs. 

Running tubes or class A SS on the high frequencies and something more efficient like a class D on bass can make sense too.       
If bi-amping is excellent then active speakers are the next and fantastic logical step - get rid of those lossy crossovers altogether and totally eliminate intermodulation distortion by asking the amp to only amplify what the driver is required to output!!!!!
I see a KEF in your future...

The very best design would be to put a DAC in the speaker with the amp, and just send control signals to it.

not sure the realization is quite there yet
Realization is quite there already : AVI ADM9.1 already have Wolfson DAC's in the speaker.
Agree that active loudspeaker is the next logical step.  There are a large number of fully active loudspeakers that accept a direct digital input signal (B&O, Meridian, Dynaudio, Genelec, Avantgarde, Focal, etc.).
I am 90% sure which brand of amp I want to get, just trying to figure out if I should bi amp or not.

as a example should I go with

two 2 channel amps at 400w x 2 so each speaker would get 400x2

or should I go with a single 800w stereo amp so each speaker sees the same 800w, just with one channel of a amp
According to this datasheet the "power rating" of the Kappa 8.1 is up to 300 watts. So an 800 watt amplifier would presumably be overkill, as would two 400 watt amplifier channels per speaker. Also, I’ve read that the 8.1 is not quite as current hungry as the Kappa 8 or Kappa 9, which if I recall correctly have notoriously low impedances in the bass region.

Given that, as well as the 6 ohm nominal impedance of the speaker, it seems to me that the best and most cost effective approach in this particular case is likely to be a single stereo amplifier having an 8 ohm power rating in the area of 300 to 400 watts, and a 4 ohm power rating of double those numbers or close to it.

Keep in mind that part of your amplification dollars goes toward watts, and part goes toward sound quality. Therefore paying for watts that won’t or can’t be used may misdirect some of those dollars.

But to answer your more general question:

In the case of passive biamping (i.e., without an electronic crossover "ahead" of the power amps) the main benefit that can potentially result in most circumstances is that each amp channel will only have to supply current and power in part of the frequency range. Which eases the burden on the amp, and can potentially improve its sonics. Also, in the case of vertical biamping (i.e., assigning one stereo amplifier to each speaker) the sonic effects of inter-channel crosstalk that may occur within the amp, if any, are presumably eliminated since both channels of the amp are provided with the same signal.

In the case of active biamping (with an electronic crossover "ahead" of the power amps) each amp channel will only have to supply current, power, and voltage in part of the frequency range. Which can provide further sonic benefits, increase flexibility in choosing amplifiers, and make it possible (although not necessarily practical) to eliminate the speaker’s internal crossover.

Biamping is a more complex undertaking than a lot of people realize, however, and can in many circumstances do more sonic harm than good. Especially if non-identical amplifiers are used.

Good luck. Regards,
-- Al

I've not found that biamping works all that well but there are a ton of variables.

Two of them are amplifier quality and speaker quality.

A third is the quality of the crossover- which is certainly one of the more important variables!

Now the amps I play at home can go to 2Hz with full power, and yet do mids and highs quite well (they are tube amps after all). My speakers go to 20Hz so I run the amps full range. I find that quite often a poor electronic crossover means that you can't get the speakers to blend and often you loose detail (since the crossover is an additional block between the source and amplifiers). I've experienced this a number of times (and used some pretty high end crossovers).

So- success is based on extreme care! If the crossover is designed for the specific speaker used I think you will have greater success.
Perhaps monoblocks would be a better option than bi-amping? Two matching amps, driving each speaker has major improvements over a single stereo amp. Due to each having its own power supply, greater separation, and generally they are the better amps a company makes. 

When bi-amping, you've got to be careful with amp matching. If you run two amps of the same size, the bass could seem weak. If you run a larger amp on the bottom, the bass could be too strong. So, careful matching is required to be sure each half of your speaker is running at the same SPL. When you drive a speaker with one amp, the amp sees the speaker as one load, the designers have designed the crossover to level them out, to keep top and bottom at the same level.  But if each amp is seeing a different load, they can react differently, causing your sound to be too much bass, or too much treble. 

There are speakers built for bi and tri amping, with a crossover that comes before the amps, or active crossover.  So each amp only has to work with the frequencies of the speaker it is driving. And can give fantastic performance, but amp selection is highly critical. And the active crossovers usually have a volume control to help with balancing. 

Bi-amping can give amazing results! But, it can also cost a lot of money, and cause a ton of headaches trying to balance the system. Since money is always a factor, all of your money invested in one amp and one set of wires can be more cost effective than halving your monies to buy half as good amps and half as good wires. Assuming we get what we pay for. Can two $3,000 amps sound as good as one $6,000 amp? Can two $400 speaker wires sound as good as one $800 wire? Debatable. 
the bass could only seem weak if the amp runs out of power - and that is less likely when bi-amping

monoblocks & bi-amping both are expensive as pointed out above - you need more transformers for the power supply

one driver, one amp is the ultimate design - you just have to create a cost- and SQ- effective realization

not that amps are a major determinant of SQ compared to speakers, room and source recordings anyway
Thanks for the input/options everyone... it has helped however I still can't decide :)

i am actually leaning towrds trying a class d amp from d sonic.  Debating mono block, stereo or multi channel.  I did visit a local audio shop yesterday, they mentioned they had a NAD 5 channel class D amp at $4k, Anthem 5 channel A/B at $5k and a McIntosh 7 channel A/B at $6,500.  I mentioned/asked about multi channel vs stereo/monoblock and his response was since I use a AVR (Integra DHC 80.3) that I wouldn't see any benefit from mono blocks or a 2 channel amp.  If I didn't use a AVR then yes monoblock or 2 Chanel amp is much better.  

I am leaning towards trying class D due to moving into a old home, built 1865 thus not the best electrically in the place.  I worry that if I go with and amp that's A/B that it wouldn't get the juice it needs.  One of these days when money is willing I will run 1-2 20A service to where the stereo stuff is but that's going to be a while.  

Yes, my 8.1's are rated around 300w, however for a really long time I have been one who likes having more power then less power.  I prefer my ears say no well before the amp or speakers say that's to loud! For whatever the reason I have always thought it just sounds better that way feeding more power.  I also hope to get a better old infinity speaker at some point.  Possibly just the kappa 9.1's or their renaissance 80/90 or preferably something from the IRS line.  Thus trying to think ahead so whatever I buy now will have enough oomph to power whatever I get next... which will be a few years down the road. 

IMHO, you should use the money you have to upgrade your electricity. It shouldn't take more than $1K, unless you live in a Victorian manision, them maybe a little more.
Has your current electrical system been renovated recently(10-20 years)? If not, then that may be a way to significantly upgrade the performance of your components, you'll also have piece of mind knowing you aren't overloading any circuits. You can also have the electrician put in a whole house surge protector.

Viggen - 

I'm currently running a D-Sonic that is a 7channel setup w/ both front speakers bi-amped and couldn't be happier.  As far as config, you can go with whatever you specify and remember, even in a 7 channel chassis, each amp is discrete as would be a mono.  

In my system, my speakers are hard to drive and go down to 2.7ohm so I'm running 2KW (4ohm) to each speaker (nautilus 800) and compared to lower-powered A/B amps I used previously the D-Sonic takes absolute control and drives these things as they were intended.

As for AC noise/ power, you obviously know already that class D amps inherently resolve that issue and this amp is 100% dead silent.  Once you get used to the fact that class D is a nonlinear pulse wave modulated architecture with incomparable immediacy (compared to class A or A/B) I think that you will be pleased.

If you end up going the D-Sonic route, my recommendation is to get the highest output modules that fit within your budget now so you can be sure that you never outgrow the amp if you ever decide to change out your speakers.

Let us know what you end up doing.

Take care

In bi-amping, each amplifier drives a less complicated load.  The drivers along with the crossover components have a complex impedance.  It consists of a real load and then the imaginary part  based on inductors and capacitors.  This complex load also varies depending on the frequency of the signal.  So if you have a 2 way speaker, the complete load a single amp will see is driver1+driver1 crossover+driver2+driver2 crossover.  This is a much more complex load that the amp sees vs just driver1+ driver1 crossover.
You got this right. "is it that I simply doubled the power that resulted in better sound, mostly noticed the low end of the speakers was tighter, more powerful etc.... and obviously I could also play louder.  

Or is is there something about letting one amp not work as hard due to only running high frequencies while the other amp gets to just work on the low end."

It all boils down to how many circuits are executed between the source signal to the target speaker. Each circuit introduces its own noise and distortion however minor. So when the unamplified signal goes into a dedicated circuit of HF amp to HF speaker cones and the same unamplified signal goes to another dedicated circuit of LF amp and LF cone, each cone can pull as much power as it needs for the track without affecting the other circuit.

When not bi-amped, the speaker wires carries the entire load of amplified current to the speaker and the speaker filters are the only ones separating the LF current from the HF current.

Bottomline: The closer to the source you separate the current, the nicer it will sound. Nicer being subjective as some listeners do like a bit muddier tone for certain music. 
I am not a fan of bi-wiring, but bi-amping certainly has its merits.  Imagine what the power supply and power transistors are going through in an amplifier to produce full range music.  For bass transients, you have large capacitors being depleted and recharged within milliseconds, and large amounts of current rushing through the output stages for every bass note.... at the same time, that same amp is expected to deliver extreme clarity and stability in the midrange and up.  That's a tall order.    
Now imagine you could separate those jobs.  To have an amp that can focus all its resources on just the critical mids & highs, without huge rushes of current to deal with the low frequencies.  Of course it will do a better job of it.   All it takes is twice the money, twice the space, and twice the power.   Is it worth it in the end.  I dunno.  Maybe one amp, twice the price, would sound better.


As discussed extensively below, the solution for the first two issues an active vertical biamp combined with low impedance cabling. The second two issues are addressed by balanced interconnects and reducing power amplifier gain—one of the odd things about audio is preamplifiers don't actually amplify. They attenuate. Line level out of a CD player is a few hundred millivolts RMS, but typical voltages at the drivers are maybe 100 mV RMS. In order to achieve a couple hundred watts of output power, power amplifiers have voltage gains around 30 dB. The preamp therefore ends up attenuating by 50 dB, meaning RMS voltages in preamp output stages, active crossovers, and power amp input stages are hundreds of microvolts. This exacerbates pickup of ground bounce or supply ripple coupling into power amp input stages and degrades op amp performance. The fix is simple; turn the power amp down and the preamp up. In an active biamp, unity power amplifier gain generally provides sufficient SPL and increases the SNR of most parts of the signal path by 30 dB. A secondary benefit is op amps behind the preamplifer's volume control operate closer to their line level sweet spot. With current generation op amps such as the LME49740 the benefit is small compared to speaker and power stage limitations, but there can be noticeable improvement in the volume control IC or with older op amps.


You are doubling not only your watts, but your power supply and head room. Addind a second, identical preamp has also made a difference in my system, because I can now have a bass control without changing any phasing through crosdovers. Since my amps do have huge power supplies , I have gone from bi-amping my mains to renning the second system on nicely matched subs.
Good point on redoing the wiring first.  However if I don't buy a amp I can't listen to my stereo. 

Its a old building as as I stated, 1865 is when it was built.  It's actually a apartment above one of my funeral homes, taking advantage of free/no rent for a while.  I believe I have a fuse panel upstairs in the attic so it probably will not be that difficult to rewire.  Paint, carpet then I need to find  out where the stereo sounds best before I run new power lines to a wall.  

This thread has been informative!!!  Thanks again everyone for their $.02 :)  I am still leaning towards bi amping these speakers, just need to figure out how much power to go with.  
Since you are dealing with old wiring, I would get an electrician to look at what you have, before buying an amp. 
If it will tax the existing wiring, you will not only not hear what you could achieve, but might not only damage your equipment, but may exacerbate a fire. Going over 200wpc is really sucking up juice.
audioman201581 posts02-10-2017 9:16amIn bi-amping, each amplifier drives a less complicated load. The drivers along with the crossover components have a complex impedance. It consists of a real load and then the imaginary part based on inductors and capacitors. This complex load also varies depending on the frequency of the signal. So if you have a 2 way speaker, the complete load a single amp will see is driver1+driver1 crossover+driver2+driver2 crossover. This is a much more complex load that the amp sees vs just driver1+ driver1 crossover.

Theres less complication by eliminating the passives it also equates to zero heat being generated within them relieving that much more strain from the amplifier. If the speakers have large complex crossovers with 1-3 big coils and 4-5 big caps you could be freeing up a good percentage of power that can then be routed directly to the drivers

I had once put together a small 30 x 4 channel Nad w Ashley pro crossover used to power some rather large mediocre efficient home made speakers, it did a fine job. Around $500 bought quite a lot of fun
I have used an active bi-amp topology for both Magnepans and Martin-Logans: preamp - electronic crossover - amplifiers. Sounded vastly better than stock, mostly because an electronic crossover only has to shape a tiny signal, and so very high quality components cost little. Think of the difference between dividing the water from a roof drain and dividing the water of the Mississippi. I used Brystons for the bottom and Atmospheres for the top.

But there is a better solution, which I use now. Why not use a speaker with no crossover at all? Quad electrostatics, for example. Save all that money for an active crossover, extra amplifier, and all that extra power, and invest in a better speaker.

Also, if you're doing wiring anyway, consider wiring in an isolation transformer, which gives you the ultimate clean power. Makes a difference you can hear, as well as protects your equipment. Word of caution - they can growl when they are doing their job, so keep them away from your living or listening areas. Plitron makes a good one.
atmasphere is correct.  Bi-wiring does not always equate to better sonics IMO.  I find it hard to understand most of the threads on audiogon that do not explain what the outcome is that someone is looking for.  What is it that you want form your system?  More watts do not equal better sound.  With the original Adcom amps the 100 wpc amp was better sounding then the 200wpc amp.  It is hard to build a more powerful amp and get better sound form the lower powered amp.  You just cannot double the parts.  Better sound as I have stated too many times already IMO comes from the source.  An amps current also has an impact on the sound.  I have an old Lafayette kit tube amp that is 35wpc and will drive most any speaker out there.  It was build using fantastic transformers.  Class D amps are relatively cheap so you and buy them and try them to hear what they do in your system.

Happy Listening. 
I will whole heartedly agree that bigger doesn't always mean better, even given amps are similar build and quality. Or that biamping is your ticket to sonic heaven. Everything has to have that "magic" brew and work together. Amplifiers have sweet spots also, and seem to sound very best in specific ranges.  

I hope that old all power amps sound the same argument doesn't resurface.  
i went up into the attic to look at the power panel, I was curious how easy it will be to bring a 20a or two service into my front room and also my bedroom.  It looks like I have several opening to run more power, I counted eight available slots so I should be good.

i also do not think it will be to difficult to run the new power wires into the rooms, being a old house they aren't the standard 2x4 construction but 18+ inches of brick, rocks etc.  Thus the power cables will not go through the wall but on the wall where I can see it in the room, that's how the present wiring is (has a aluminum covering).  I think the access from attic to room shouldn't be to bad.  

In my experience, bi-amping has not made my systems sound better other than improving bass performance. Bass can be cleaned up or controlled with bi-amping or the midrange and top can be improved with the adding of power of bi-amping but I feel the system will sound more complete and whole when it is run on a single amp that has enough power for the speakers. 
Well...  being a old house I needed some plumbing work done,  toilet swap, faucets, garbage disposal and shower controls.... I was worried a little job would become big if I did it myself.  Long story short it did still become a major job, found several leaking fitting behind drywall in not so easy places which resulted tiles are falling off around the PINK bathtub...l thus my buy amp now money is need a shower/redo bathroom money,

Bi-amping can allow some amplifiers to maintain their Class A bias longer.
I feel your pain, but an old house has more character than a new one.
Hopefully, eventually, you will get to the wiring. And, as you said, it should be an easy upgrade.
 If code permits, and you can run new wiring without needing conduit, it should be a slam/dunk. I posted a thread a couple months ago regarding a whole house surge protector. If you do get around to re-wiring, I encourage you to consider adding one. They don't cost much and can give you some piece of mind, as being one layer of protection.
Vig, just saw this thread.  One question for you.  Have you spoken to your dealer about your situation?  It sounds to me that for the money, you may want to consider newer speakers first rather than sink money into new electronics.  Eventually doing the electrical will help, but with the new technology, speakers have come a long long way. 

I have a pair of Vandersteen Quartro's being shipped this week.  I upgraded to them in order to get an active sub built in.  The main amp will now only be responsible for sound from 100hz on up, so it frees it up greatly and will improve it's sound dynamically etc... Yes, I also bi wire.  Some designers don't are about bi wire.  This is why I try ti personally purchase 'system's' and not just randomly get a well reviewed amp, a well reviewed speaker and and a well reviewed DAC or TT.  

What is your budget?  If you sold your speakers, what would your budget be then?  It's just a thought.  Heck, my Ayre AX5/Twenty like all Ayre products has filtering built right into the unit.  I plug directly into the wall and it sounds it's best.  From the amps you mention, it all seems to be about the largest number of watts you can get, however the majority of great speakers don't need that much to sound good.  JMHO
I have Avantgarde Duo-Omega gen II, 16 ohm. I am using the Ultra-linear OTL, one stereo amplifier for each channel, full range, so no electronic crossover in the signal path. The left and right inputs on each amp is combined with a little internal wiring change to avoid using a Y connector. The right channel output goes to the bass and tweeter. The left channel goes to the midrange horn. I did it this way because the midrange horn has no crossover, so the voice coil is connected directly to the amplifier. The sound is much better than running the amps in monoblock mode with double the power driving all the speakers. In the configuration I have, the output is 20 watts per channel. With the speakers have a sensitivity of 107db, there is plenty of power. This is the reference system in my home, where I test our cable designs. 
intersting.  Thanks for sharing.  There are so many ways to set things up.  It all comes down to personal tastes (as it always does) and how speakers are designed.  This is why I always ask whatever designer made my speakers, what they recommend and go from there.  

Heck, I need an external crossover for my Vandy's and I had Ayre build it into my integrated amp so I could cut out some extra connections, plus they used premium parts as does Vandersteen, so I didn't lose anything.  
A long time ago I used a bi-amp setup with two Rega amps into a pair of Proac D-28.  The improvement over using one amp was very noticeable-night and day.  When I sold the amps, I talked someone into buying them both and try the bi-amping and that person fully agreed that the bi-amping made a big difference. 

I forget which way the bi-amp sounded better but I do remember trying it both ways; with one amp powering the left speaker and the other the right, and with one amp powering the left and right woofers, and the other amp powering the left and right tweeters.  But I do remember that while it was close there was an improvement doing it one way over the other.  I think that is worth experimenting with both methods so you can find what works best. 

I did not test to see if one more expensive amp would have sounded better than the two separate amps.  But my guess is that while a better amp sounds a bit better than one that is half the price, I just don't see the improvement being as dramatic as what I heard from bi-amping.  So I am a believer in bi-amping based on my limited tests. 
because the amplifier that feeds the tweeter and midrange is not burdened with reproducing bass - which takes multiple times the power.
in a single amp configuration as the burden of reproducing low frequencies taxes the amp, the clipping can be heard as strain or glare through the midrange and tweeter. not good and very tiring to listen to.
with a bi amp configuration the midrange and tweeter amp can coast along unstrained and never clip.
also the midrange / tweeter are isolated from the clipping woofer amp.
clipping is usually not audible or objectionable at bass frequencies but it fatigues like no tomorrow at midrange and treble frequencies.
the benefits are definitely not from bi-wiring.  
I’m a long time Infinity loudspeaker owner. I think mono blocks (not bridged stereo amps) work the best and is the cleaner set-up. One set of quality speaker cables, less equipment, and less to go wrong and better channel separation. Simple systems are the best. Go for a quality amp, don’t cut corners there. If you can’t afford a pair of big bruiser amps, get one stereo amp. No AVRs, multi channel amps, or mid-range gear. Get an A/B amp, the lights will dim when the bass hits but by then it’s too loud anyway. Oh, and the bad news: Get a real stereo pre-amp. Your AVR is already holding you back.