I was a heavy user of AudioGalaxy because I have a huge collection of audio content including music, audiobooks, and audio drama. It was a perfect solution for me as I could also share the content with my wife. When Dropbox bought AG and subsequently killed it that was a sad day for me.
I have been searching for a viable substitute for a long time to no avail. I've tried Subsonic but it seems quite buggy; it has not updated my library since the initial scan even though I've added many new files to the folders it is supposedly scanning.