Alternatives Software for iTunes on Mac

Another vote Audirvana. I’m not aware of better audio playback software for Mac. It can also stream Tidal from within the app and you can remote control it with your phone.

MacX MediaTrans

• Back up your photos
• Manage your entire music library
• Transfer videos to and from your phone to other devices
• Encrypt files
• Manage voice and create customized ringtone as well
• Organize your books
• Use your phone as a flash drive

@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.