I am successfully running the Id Pi now, and after doing some research I found answers to most of my newbie questions. It plays DSD128 gapless, which is great. SACD ISO is working fine, and I was able to import my files off the NAS once I checked the "extended file names" option, since it was crashing before.
From the conversation above, I understand that once the 4.9 kernal is officially released in Raspbian, you will incorporate it into an update for the Id Pi. I guess I will wait on purchasing the Digi+ Pro board until then. I also understand now that SPDIF will only pass up to 24/192, so I would have to convert DSD to 24/176.4 on the fly.
I have a few new questions:
1) the sound level of the Id PI is lower than the USB output of my laptop. Is this a Pi hardware issue, or a software setting? I have volume disabled on MC22. The sound seems sort of tinny, or like the digital level is not at 100%.
2) Is there a way to always boot into command line, or do I have to reboot from panel into this mode?
Thanks!