Where do you get the digital X-over from?

Interestingly enough my Onk has two separate outputs per channel for the front. One of the outputs is for bass and mid-range and the other is for the tweeter. You can configure your own X-over in the setup. I've never tried it but have always wondered how well it works.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated