New theory for cost-aware 4-way XO on Rpi5: get the cheapo Behringer UMC1820 and use its analogue outputs for sub bass and bass, but use external stereo DACS (present) for mids and highs, connected to the digital outputs of the Behringer (S/PDIF and ADAT). The Behringer should keep all channels in sync.
(Same principle could of course apply for other cheap but well equipped USB interfaces, perhaps there are better choices than the Behringer.)
(Same principle could of course apply for other cheap but well equipped USB interfaces, perhaps there are better choices than the Behringer.)