Multi-channel usb powered DAC?

[The Fat Bastid]

Hello all!
A car audio question.
I need to make a connection between a raspberry pi 4 headunit and a minidsp c-dsp 8x12. The c-dsp's digital inputs are 2 channel only and I'd like the option for 5.1 if someone watches a movie so I'd like to use the 6 analog RCA inputs but keep the digital signal as long as possible. At first I was thinking of an hdmi audio extractor from the pi's hdmi output but I think a cleaner solution would be a usb powered multi-channel DAC. (this way a usb cable can be run to the trunk without the need for another power wire and turn on relay)
Most usb dacs seem to just be stereo and the only multi channel ones I can find are:
https://www.esi-audio.com/products/gigaportex/ not on sale yet, pro audio stuff.
https://www.asus.com/us/Sound-Cards/Xonar-U7-MKII/ computer stuff
https://us.creative.com/p/sound-cards/sound-blaster-x-fi-surround-5-1-pro also computer oriented.
I was leaning towards the gigaport ex, the current gigaport hd seems outdated. This seems overkill as the c-dsp will handle all the EQ and crossover, etc. but I'm not sure if there an easier solution or better option?
Does this plan make any sense?
Thanks all you smart people!

 

[Jose Hidalgo]

Hi @The Fat Bastid , have you found a solution to your problem?
There are some multichannel DACs, but they can quickly be pretty expensive.
My favorite would be the Okto Research dac8 Pro.

 

[Daverz]

Motu Ultralite Mk4 perhaps? Around $600. Don't own one, just interested in similar devices myself.

Sorry, not bus powered. Perhaps Motu will come out with an M6 or M8 to complement their M2 and M4 bus-powered devices.

 

[The Fat Bastid]

I talked to a few people and they mentioned two things. 1) don't use home stuff in a car. 2) 5.1 stinks in a car anyways. So I got an Allo Digione to feed the minidsp's s/pdif.