Am I wasting money on the theory of Bi-amping?

Just my opinion, but the difference between bass drivers and midrange/tweeter drivers FAR exceeds the difference between comparable amplifiers. Except of course for planar-magnetic’s, ESL’s, ribbons, etc. Different drivers made of different materials sound radically different from one another.

Amplifier designers have to make compromises in their amps: bigger output transformers in a tube amp produce better bass than does the same amp with smaller transformers. But smaller transformers produce better high frequencies (smaller ones create less saturation of the transformer core, a consequence of magnetic flux).

Of course the above pertains to only tube amps. But ALL amplifiers are designed with compromises made. Using different amps for different frequencies makes a lot of sense. Everyone with a subwoofer is already doing exactly that.

Totally agree with Mike L.   He's dead on.    Waste of money for most people because seldom is it done correctly.   It's expensive to do right and the complexity just isn't worth it in most systems.   Upgrade the speakers or amplification for real noticeable improvements instead.  

It’s not a theory

Forget techniques of setup for the moment

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IF you have a ’not so powerful’ amp that you love

IF you have speakers with large woofers, or even subs that are not self-powered

Then, to get more power for the demanding bass frequencies, you bi-amp, size your bass amp for both strong fundamentals/overtones, and enough control to work with the woofer's magnet to stop the woofer

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IF you have enough power, I do think bi-amp based on ’this cable is better for bass’ frequencies, this ’other cable is best for mids/highs’ is ......................................

If you can afford it, like many other ______, why not, unless you lose something messing about.

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This made a slight difference, a big difference, a huge difference.

Ten ’upgrades’ all made a slight, big, huge difference: oh my god, gotta be the BEST system you ever heard! Gotta be.

The issue is half in the speaker, half in the amp.  Lots of speakers have challenging loads in the bass, and lots of amps can perform better with better power supplies.   Notice this is kind of statistical.  I say "lots" and "most." So, while bi-amping may help, it won't always.

When you bi-amp you double the power supply and output transistors, therefore making the amp less sensitive to impedance issues. 

Whether or not it helps you is something you should hear for yourself.  Generally you should hear better defined bass and transients.  If you don't hear that you may as well sell an amp.

My first "go" at this was many years ago when I got my Genesis V speakers that came with an outboard amp/crossover and used my VAC tube amp on top. My next setup was the internally powered Golden Ear Triton 1.r speakers which also "bi- amp" the bass. I recently got rid of them in favor of the Legacy Audio Focus XD speakers that are "bi -Amp" speakers. They have an internal amp in them. I am now in the process of doing this right and have ordered their external crossover Wavelet II which will go between my VAC pre amp and the speakers as well as my VAC tube amp for mids and highs. The Wavelet will then feed to the speakers internal amp and my external VAC amp simultaneously. So far all have worked out for me, yet this final ventures is yet to be determined although it may most likely be the best of them all.