Alternatives Software for iTunes on Mac

@joscow  What do you mean by "high quality"?  When you send music over wireless you really send data.  No matter what program you use it is still the same data (no timing involved), unless program modifies it somehow (like upsampling), making data not "bit perfect".  Make sure to set playback volume at max.  Playback program can affect quality when it can affect timing (jitter) of the D/A conversion.  It can happen when you output data with S/Pdif cable.  

I also use Itunes with Airport Express.  The only complain I have is clumsy interface.  I created "Smart Playlists" for each genre (for instance: "match music for the following rule: Genre is Classical") and select playlists.  It places thumbnails for each record - about 21 on each page. Much easier to find each record.

@joscow, What problem are you having with iTunes? Maybe it can be resolved. Like you I have been using iTunes for a long time. I still use it to wirelessly stream my AIFF ripped CDs to an Airport Express or Apple TV and have not encountered any problems.

I forgot to mention dropouts.  I had dropouts because at lower band 2.4GHz there are only 3 independent channels (since each of 12 channels is almost 4 channels wide).  I bought dual band router, switched to 5GHz and problem is gone.  5GHz has more channels and poorly penetrates walls making it difficult for outside signals to enter home.

ijgerens- for 6 weeks now,Having a problem with intermittent dropouts, hanging, and complete freezing resulting iTunes quitting. Sent reports to Apple. They elevated to engineering 3 days ago but have heard nothing from them regarding solving the problem. Now, it cannot get it to accept the current library. It has an old library that doesn't contain some of my most recent downloads and purchases. your thoughts

@joscow  Sorry to hear that.  I have I tunes Version 12.9.5.5 running on late 2014 MacMini with Mojave Version 10.14.6 and have zero problems.  I changed library, but it was long time ago.  There is Itunes media location (Preferences => Advanced) and Library name (Preferences => General).  All my files are under folder Itunes/Itunes Music.  I have marked (Preferences => Advanced)  "Keep Itunes Media Folder Organized" and "copy Files to Itunes Media folder when adding to Library".  When I point to any folder containing music and select File - Add to Library it adds listing to named Library and copies files to "Itunes media location".  You can start new Library with new name and media location and then add any file you want.  

I had dropouts with 2.4GHz but never hanging.  How much memory you have.  Exit programs you don't need.  I hope it will help.
I went thru many versions of OS and few Macs and never had problem with Itunes.