Given the trouble I had getting some things to work, I was pleasantly surprised to find that Hi-Fi Cast was pretty much plug-n-play. It automatically found the DLNA server on my NAS and Volumio on my Pi Zero W. The interface is super responsive, but my Synology Diskstation server wasn't serving up album art, so I installed MinimServer. It seems to be very streamlined and scanned my library very quickly. All album art is now appearing on Hi-Fi Cast, and no crashes or hangs so far. And as a bonus, I can stream gapless to the Chromecast on my TV/2.1 system. Not sure what bitrate/codec is being used, but it'll do for background music.