Who makes a digital crossover?

Does anyone make a crossover that works in the digital domain.
I may be showing my ignorance here so I will post it as a question instead of a statement. What about using the crossover in a digital processor such as an audio/video preamp and running it in 2-channel mode? There are several made to varying degrees of quality. Why would these not work? Mine works in 2-channel mode when I play CDs on my DVD player that decodes HDCDs. Comments welcome.
Thanks and good listening!
I looked at accuphase, rane and dbx and I'm pretty sure they all take a digital signal, convert to analog and then offer analog slope crossovers. I couldn't find XTA. Anybody else?