>>> So would you be able to have your nas hooked up to a dac, and tell alexa "Play miles davis" and it will output miles davis to your dac? I DON't want it to go to the alexa device...I also want to be able to play flac and dsd files.
I don't think this is in the near future as you describe it, but this is what you can do with a NAS and an iOS phone or tablet, and a great app like Music Streamer. I do not use FLAC files for music (they are very large files that take up a lot of disk space) so I use a variety of mp3 file formats Files I make are at a higher quality than the standard mp3, (e.g. higher bit rate and other tweaks) -- to me the files sound exactly as good as the CDs they came from. Music I download from eMusic service are mp3 files and their quality is a mix of bit rates depending upon when they were made. Most all new ones are 320 bps.
OK, so back to the NAS idea, the NAS stores all these files and delivers them to the player as mp3. flac or whatever files. So in the case of flac files both the NAS and the device it is sent to both need to handle the various audio file formats. This can be a roadblock for devices. I standardized on mp3 early on (and not Apple ACC files), for example, because I wanted my digital files to play on anything; then and into the future.
A NAS is a device with a few large hard drives inside with lots of capacity (if needed) and it connects (not like a hard disk does to a computer) but it connects to the router -- media files can be distributed anywhere the home network is; wired or wireless. No PC needs to be on. A NAS can be running 24/7 A NAS can do more than I mentioned here (like be accessible remotely away from home).
To learn more about a NAS and what it can do I suggest you go to WDC.com and look into the top of line WD NAS (aka, Network Attached Storage) devices, the PR2100 and PR4100. (I have a model that preceded the PR series.) A NAS with the appropriate files compatibility can easily store and send your music files onto the next processing device.
As for asking it to "play Miles Davis", (Which Miles Davis track?) is NOT something Amazon is interested in doing, but eventually some company will do it. Meanwhile, I can get real close to this using a "retired" earlier iPad, and the Music Streamer app.