Fosi Audio Q4 DAC Headphone Amp for PC, Desktop Digital to Analog Audio Converter for Home Stereo Amplifier and Powered Speakers, PC-USB/Optical/Coaxial Inputs, 3.5mm Headphone/RCA Outputs

Find a used AVR or stereo receiver that has optical… no reason to dump a ton of money into the situation. Can literally find one for $50-$200 on Facebook marketplace and you’d be good to go. HDMI ARC or Optical > the receiver > the speakers with some speaker wire, done. Other route would be a DAC & Amp… but honestly, used receiver route will likely end up cheaper (I’d only go the dac and amp route if you want brand new, but don’t let brand new end up more than what it would cost to get a refurbished AVR): get this - FOSI AUDIO DA2120C … other options are a combo of these two, FOSI AUDIO Q4 & BT20A Pro (or the non-pro version, but I like the pro more)… WiiM Amp is also a nice option, but it’ll cost more than the prior two options I gave. Best choice is the DA2120C (best for beginners) for simplicity purposes. You go the Q4 & BT20A Pro route if upgrading speakers down the road and amp performance means a bit more to you (since it’s two separate pieces of hardware, you could always choose to keep the AMP and go for a better DAC as time passes).

All speakers are working, I have the audio cables running from the audio board in each cab running to a DAC / amp, which is then feeds to an HDMI splitter. The output audio cables from the DAC /output HDMI monitor cables from each monitor / input HDMI cable from the GPU plug into the splitter.