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



128x128viggen900
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

Greg
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.