Hi there - which Dac are you looking to use? I'm currently using Piano + Kali ( Kali made a huge difference ). I was thinking about getting a Prism Callia - I may still get one to demo, they are rather expensive and you still need a streamer! - Thinking about external Dacs / streamer was what led me to Pi platform and external Dacs as a good fairly low cost way of finding out if my aging ears with a bit of tinnitus could still tell the difference - happily they can. Anyway, looking around at hi-end Dac chips I believe that the Cirrus CS4398, beloved of Prism, would be an excellent choice. I could design a board using one of these but, not being much of a software engineer I'd have to nail it at 44.1 / 16 bit - fine for my large library of Flac rips, but rather limited and of no use as a complete solution.
I'm professional hardware engineer - many years at AMS Neve and Calrec before setting up on my own 12 years ago - www.jlhsystems.co.uk. Regards, John Haughton