HTPCs no longer make sense for modern media playback. I use a PC as a Plex server but use an Nvidia Shield as the endpoint, so it can playback the full quality of 4K UHD rips, as well as serve as a much better streaming device than a PC. For music, I use Roon so have an Intel NUC running Roon ROCK OS, directly connected to my AVR. With this setup, I get full quality movie and hi-res multichannel music playback, both with wonderful organized display systems and none of the limitations/hassles of Windows/MacOS.