I am another old guy still trying to figure out the ins and outs of streaming. The ML Unison seems like an incredible deal right now but I read this review and it has me wondering if I have to bypass my outboard DAC in order to get the ARC.
“This is when the DAC inside Unison comes in. It does its job and it sounds quite good, but don’t expect the performance of a high end DAC. Having a power amplifier, I had to play with the volume from the Play-Fi application and I found it a little hard to get my desired volume, as it’s not very smooth. However, it did its job and it was really easy and convenient to access and to listen to my favorite musicon Tidal. I was wondering if I can use the Optical Input from the TV to Unison and the Unison to my DAC and still use the ARC correction software, but it didn’t work.”
https://headmania.org/2018/02/03/martin-logan-unison-review/