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

I’ve done a lot of bi-amping, tri-amping, all the way up to 5 way active speakers. It’s all a pain in the ass. If you’re not building your own speakers, it does seem fair enough to call it a waste of time, energy, and effort to bi-amp a speaker that already has a well designed passive crossover built in. However, you might actually like the results, so if you don’t mind the effort and expense of exploring and experimenting, then I would recommend giving it a try. My own experiences with passive bi-amping showed no obvious benefit. I was using solid state amps with plenty of current capacity, and the speakers were fairly sensitive and efficient, so that may have a lot to do with it. If you’re building your own speakers, making a passive crossover network can be a total pain, add up to a lot of expense. You can get active crossovers that include all kinds of shelving, notch filters, parametric EQ, time alignment, etc., assuming you’re willing to go digital. You can also hand pick your drivers so they don’t have any issues in the passband, and get what I think are some pretty stunning results. The active crossover lets you experiment quickly. I have read that a passive crossover never sounds highly transparent, although I think good ones are transparent enough in typical listening rooms. This is one case where people were easily able to tell the insertion of a passive network vs a pure feed in a double blind test. The testers were unable to make a passive network pure enough sounding to fool anybody. A digital active crossover could fool people. Whatever that’s worth, it does seem that for the ultimate in sound fidelity, a digital active crossover has more upside potential. Doesn’t mean you’ll like it better. Just means you’ll have a harder time telling it apart from a pure feed.

In case you’re wondering how these tests were done, they used headphones, split a signal into a low pass and a high pass, and the recombined them to a full bandwidth signal that went to the headphones. The listeners could compare direct feed to the split and re-combined feed. This allowed the passive networks to be at their best, feeding in to very stable, pure resistive loads. (I actually can’t remember if these were entirely passive or included some op-amps to make them work better. If they included op-amps some might be tempted to say that people were hearing the op-amps, but I doubt that. In any case, they were analog, line level networks.) People could easily hear the difference, even though considerable effort was made to optimize the analog networks. A passive network in a speaker is more of a mess, feeding into multiple speaker drivers with all their impedance complexities. It was interesting to me that even though the digital crossover had to do A/D D/A conversion steps, people still noticed no obvious degradation in signal. It may have to do with the people chosen for the test. Over and over I get the impression that audiophiles are particularly sensitive to things that most people don’t notice, but also peculiarly unsensitive, or at least unconcerned with things that most people can easily hear as problems. Audiophiles have learned not just to listen, but to curate particular tastes. It's not just about what is identifiably accurate or inaccurate, but what comes across as most natural and pleasing.

@asctim wrote:

... It was interesting to me that even though the digital crossover had to do A/D D/A conversion steps, people still noticed no obvious degradation in signal. It may have to do with the people chosen for the test. Over and over I get the impression that audiophiles are particularly sensitive to things that most people don’t notice, but also peculiarly unsensitive, or at least unconcerned with things that most people can easily hear as problems. Audiophiles have learned not just to listen, but to curate particular tastes.

This. 

NO! Because it is NEVER the THEORY that is the waste of money. It is always the application / implementation of the flawed theory that is a waste of money. Notice that all these other posters with multi-paragraph theories aren't wasting one dime of their money with their theories.

I have actively bi-amplified my Magnepan 3-series using an external active crossover (Marchand). You have to have a decent crossover or it’s a waste.

My take was that the active bi-amping was a complete sea change in sound. As it should be since you are using an entirely different crossover network and the crossover is before and not after the amplifier, so the amplifier is freed to fully power the drivers it’s connected to. Worked very well.

But that’s because Maggies have that biamp capability without surgery. You have to take out the internal crossover network in speakers to do this right. With most speakers I’d say it probably isn’t worth the risk or effort. The speaker designer had the crossover network in mind. Magnepan clearly had active biamping in mind.

So, in limited circumstances it can be a huge improvement. But, limited circumstances. Biamping without taking out the passive crossovers is just a bit more oomph in power but at the cost of a lack of consistency. I wouldn’t do that.

I biamp in one of my systems.  I use a pair of mono amps to handle the bass and a different pair of mono amps to handle the mids and highs. The mid/high have the bass rolled off using high quality caps at the amp inputs and there is an adjustable unit to balance the bass (which goes through untouched) with the mids/highs.

This is the system that Richard Vandersteen uses and it works very well with my big Vandersteens, although many would prefer to avoid the complexity of four mono amps with an external adjustable crossover for the bass.

Does it sound better done this way?  I was pleased to find that it does and the improvement warranted the extra system complexity.

Whether you would get the same gains depends entirely on your particular system.