I appear to be late. Sorry for reviving an old thread.
This will be a non-technical response.
Let's start with the basics:
A phono cartridge outputs a balanced signal, as does a reel to reel (tape). To keep it simple, a pure sinusoidal waveform is presented in an electrical state. Only, and I mean only, a dual differential (or true balanced) phono pre-amp will preserve the entire sinusoidal waveform. So far we are symmetrical. Imagine a sine wave.
As soon as the sine wave encounters an unbalanced electrical component (RCA interconnect), the 'falling' portion of the waveform is referenced to ground. This means the entire waveform is NOT preserved. We are now asymmetrical.
The same holds true for asymmetrical crossovers. The negative portion of the waveform is not preserved. This is not entirely true, but 'LarsS' in post #22 said it perfectly; the rear motion of the speaker (driver) is not preserved. I tried uploading relevant pictures, but no go.
Here's the problem; in order for the beauty of a symmetrical crossover to be truly realized, it must be driven by a symmetrical amplifier. Ideally the entire amplification chain will be balanced (dual differential). No one wants to hear this. No one wants to be told their unbalanced (single ended) amplifier is throwing 1/4 of the waveform away. Speaker manufacturers of symmetrical crossovers don't want to potentially lose customers because they don't have balanced amplifiers. Such is the world we live in.
If you own Gauder, Magico, or Evolution Acoustic speakers, do yourself a huuuuuuuuuuge favor, get hold of a dual differential amplifier, and listen. 50% of you will hear the difference immediately. Why 50%?, it has to do with 'spatial acuity', the way the brain interprets moving objects (sound waves are moving). Think of it this way; if you can parallel park, or if you never get honked at because you never cut drivers off, you have spatial acuity.
Sorry, the digital domain does not preserve the entire waveform.
I read somewhere; if you want to enjoy digital, never listen to good analogue.