Bi-amping???????'s

What you are suggesting is pretty much a step sideways. To answer the question, it does work. You would be indeed biamping. You do not need an external crossover to biamp, but it usually sounds better. If you didn't have to split the signal at the amp end, you would probably be gaining something, but I would guess you will have signal loss when you split, and so that will take away from anything the biamping would have acheived. Of course, this is only my opinion, and I don't have your setup, so I can't say for sure. The best way to decide if it is worth it or not is to use your ears. Experiement and see which way sounds best to you.

I am a little bit lost about :

"If you didn't have to split the signal at the amp end, you would probably be gaining something, but I would guess you will have signal loss when you split, and so that will take away from anything the biamping would have achieved"

Assuming that you have 4 identical amps(identical input impedances), using 2 sets of identical interconnects (lenght, characteristic impedance(Z0), construction, model, and termination), and a preamp with one set of output (say RCA or XLR)is your statement still true?

I thought one of the reason behind the design, for max voltage out, on preamps (RMS) is chosen so that it can drive longer interconnect without any problems of preamp loading or attenuation. All you lost is just a few clicks from the volume control. Also, for a significant degredation of signal output (or sound) on preamps of this design, the lenght of the cable (taking into consideration the characteristic impedance; resistive, inductive or capacitive in nature)will be in the order of about several hundred feet. So what exactly is lost when you split a signal for interconnects, say about 1 meter?

Please don't get me wrong, I am not criticizing your statement. I just want to understand if what is really true in this kind of scenario.

It will work fine as long as you split the stereo output from the preamp using "Y" cables or if your preamp has two sets of stereo outputs, use both pair. You will probably gain a little. But when a multi-channel amp is used as a stereo only amp, you gain some power due to the fact that the power supply only has to deal with two channels as opposed to many.

I use simple resistor capacitor filters that I put between the amplification stages of vacuum tube amplifiers and do away with the speaker crossover and all its problems altogether. If you major in physics you can calculate the values of the resistors and capacitors involved. the resistors should be equal to the square root of the product of the output impedence of the driver tube and the input impedence of the output tube. These values need not be that exact. The capacitors should have a capacitive reactance equal to the resistance of the resistor. First order crossover is one resistor and one capacitor, second order is two resistors and two capacitors, etc. Make a high pass filter for the amplifier that drived the tweeter and a low pass for the midrange. Reverse polarity of tweeter terminals if you use second order. I do not know if that will help in the future.