>If I was to unhook the wires to the woofer of my (non-biwireable) 3 way speakers, would the crossover parts that make up the low pass to the woofer still be using up energy from my amp, or is there no energy loss since the circuit is not completed?
You don't want to do that because you're going to loose baffle step compensation, the high frequency roll-off needed to sum-flat and any notch filters present.
Energy used is also the wrong way of looking at it.
Passive bi-amplification would be more appropriately called active bi-wiring because the same signal is being fed to each amplifier which is in turn limited by the peak voltage of the summed signals.
An amplifier good for 100W into 8 Ohms will swing 40V peak positive and negative, thus allowing for a 20V peak signal into each of the high and low pass filters of a 2-way or 25W per for 50W total with sine waves. I'm going to completely ignore that driver impedance is reactive and concede that's a simplification with the real numbers being more like 22V and 18V for typical 2-way cross-over frequencies for 30W and 20W for the same 50W total on sine waves.
When you split the signals before the speaker level cross-over, each amplifier sees the same input and clips at the same place it would (assuming competent amplifier design) with just a single amp. With two 100W amps, or even a beefy 200W amp on bass and 100W on the tweeter you're still getting only 50W total out (with a 3dB crest factor; 25W with a 6dB crest factor, etc).
That's not interesting.
You can come up with all sorts of pseudo-science about not having the DC resistance of coils in the picture, although their tenths of an Ohm are inconsequential against the 5+ Ohm DC resistance of an 8 Ohm driver's voice coil.
To get performance gains you need to split the signals before getting to your power amplifiers and scrap the speaker level cross-overs. Typically that's done with active circuits although passive line level implementations are also possible.
That needs to be at least as good as the transfer function provided by your passive cross-overs which includes compensation for baffle step, rising response, driver resonances, differences in the acoustic centers, etc.
Obviously none of that is present in an off-the-shelf unit or even a programmable one just set for cross-over points and slopes.
You're not going to duplicate that without measurement capabilities and filter design knowledge; so if you want to bi-amp for performance you need to buy speakers with an outboard line level cross-over or build a proven design that works that way.
