if you can find a raspberry pi you can run direct to a stereo or pi > dac (onboard or not) > stereo
I use this with volumnio but there are several other free options.
i only have some issues on wifi when pulling 24/192 playback. I havent tried to troubleshoot if its the wifi or the dac (limited to 24/96 on this particular grace)
but a non iOS option as a suggestion. it will play just about every format i throw at it. it is also seen as a chromecast device if thats appealing