USB Multichannel is the most viable option for sure.

Be careful with the levels - such a setup can easily blow the tweeters - best to insert fuses (typically 1.25 Ampere fast blow) to avoid expensive accidents.

I am looking for some practical advice from someone who knows more than me about moving my 2-way analogue active system to using a digital active crossover.

Current Setup
Speakers are Naim SL-2 with passive crossovers removed.
Power amps are a pair of Teddy Pardo MB100 monoblocks driving the woofers and a Sugden Masterclass stereo power amp (which is dual mono) driving the tweeters.
Analogue active crossover is a dbx223xs (the balanced in/out model).
Upstream of the active crossover is a RME ADI-2 Pro FS R BE used as DAC and Pre-amp in ‘DAC’ mode.
There is a Raspberry Pi streamer connected to the USB input of the RME unit, and a CD player connected to the analogue input of the RME too.

This all works fine.

What am I Trying to Achieve?
I would like to replace the analogue active crossover with a digital active crossover such as Camilla DSP running on a Raspberry Pi. I want to do this have more control over the crossover parameters/settings than I currently have with the analogue crossover.

This would effective move the crossover function to be ‘upstream’ of the ADI-2 Pro and ‘downstream’ of the streamer. It would also require me to switch the CD player to use its digital out put into a digital input on the streamer.

I know that the ADI-2 Pro has 2 distinct 2-channel DACs and that its ½, ¾ analogue outputs could in principle be used as 1=Hi Left, 2=Low Left, 3=Hi Right, 4=Low Right or similar, with some messy wiring using the front ¾ headphone output and rear ½ main output.

Question: I obviously need to feed a pair of 2-channel digital signals from the Camilla DSP output to the ADI-2 Pro, but how is this best done? Would it be best to setup the routing in Camilla DSP to send all 4 channels over USB to the ADI-2 and set that unit in ‘multi-channel’ mode, or is there some other better approach?

Many thanks for your thoughts,

David.