I want to introduce you to my recent development - software crossover for offline processing of the SACD DSD streams.
Its core based on a FIR filter and provides direct filtering for delta-sigma streams, without any intermediate conversion into the PCM.
Stereo DSD stream (inside a DSDIFF container file) on the crossover's input processed into the multichannel frequency-divided DSD stream (and also stored into the DSDIFF container) for further playback through the multi-way multi-amped speakers.
DSD offline crossover is absolutely free and can be downloaded on my site: http://dephonica.com in "Downloads" section.
Your feedback is very interesting for me, because now I'm starting development of the real-time DSD crossover (as a part of the xDSP2 software crossover project).