Apple iTunes or What Else

My Apple iTunes has 2500 CDs or records on a separate hard drive on a Mac computer. All the music is in AIFF files, and the sound is excellent.  The music is streamed wirelessly using Apple Airport Express. My amp is a current Rotel Integrated with DAC and capabilities for optical or coaxial. I use both depending on my mood. The speakers are Monitor Audio Gold 100 which I love. My question is: " What other software would one recommend if I wanted to move away from Apple iTunes. Not dissatisfied but explore a change. Software must operate on Mac OS system.
I really enjoyed Audirvana as far as sound quality goes. However, Roon's user experience and interface was super impressive. I had been using Audirvana for quite a while with my last amp. When I got the new amp I experimented with Roon. I really enjoyed it, but it didn't sound as good to me as the built in streaming software of the amp. Ended up cancelling my Roon membership prior to the end of the free trial. I noted in my reason to cancel that I wasn't pleased with the sound quality. I actually received an email from someone at Roon offering to extend my free trial and help walk me through the program to get the best sound. Never took him up on it, but was really impressed with that kind of customer service. 
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Roon will read your iTunes library but not modify it in any way. You can continue to use iTunes to add music to your library.  I’ve grown to appreciate how easy it is to use iTunes to edit the metadata of my AIFF rips done using XLD. 

Roon will stream to that Airport Express too.  There’s a free trial.  
That is really good equipment you have and I think it’s similar to what I have. I too was using Itunes and have quite a library of AIFF files on a Western Digital Hard Drive that uses WD MyCloud. Because I have a limited budget, I opted to try the Bluesound Node 2 and BluOS software. I can access all my AIFF files and stream via a wide variety of streaming services like Spotify and Tidal. There is much written about Bluesound...have a look. But for me it fits perfectly and sounds great. If you ever try Roon again, Bluesound can marry up with Roon as well. For those who want to try a better DAC with Bluesound, many out there can be used and some can also play MQA tracks.
I use a MacBook Air (latest version) with Audirvana Plus (v 3.5) in this system:

Running FLAC files and Tidal; results are extremely good IMHO. I have no plans to change anything. Well, maybe upgrade the McIntosh C50 to a C52.

I recently upgraded my HT Oppo UDP-205 DAC to run MQA (free firmware upgrade from Oppo) with the MacBook Air; speakers are B&W 802D and Krell TAS 5C amp. Again, results are very impressive running Tidal MQA. Once again, I have no plans to upgrade anything. Well, we shall see!

I find Audirvana Plus very easy to use, especially with Tidal. Overall sound quality is outstanding. Very happy with this setup,


Like you I have been using iTunes for over 8 years to stream my AIFF ripped CDs to either an Apple TV or Airport Express. I have 3 systems in different rooms and my wife has her own system. Over that time, I have never had any issues with iTunes. No dropouts or glitches, it just works flawlessly and the sound quality is great.  So, I have no plans to change anytime soon.

I would remind you that Apple will be replacing iTunes with three individual, standalone versions of their Music, Podcasts and TV apps in the next version of macOS. You might want to wait and see what the iTunes replacement is like.

Thanks for the suggestion re Apple replacing iTunes. That has to be a consideration. Need to know what apple will do with iTunes.

Like many of the comments, I have used iTunes since the beginning and like its sound quality particularly AIFF files and ease of use.I am going to evaluate and study Audirvana Plus, Roon, and Bluenote. Have been downloading a number of high resolution music from HD Tracks and they really sound good in iTunes. Tried Amarra a few years ago. It had too many issues for my system and didn't sound appreciably better than iTunes. 
I use Itunes with Airport Express on 5GHz with no dropouts (Mac Mini). What is being sent to Airport Express is compressed data in packets (not in the real time). Programs, or anything else, don’t make any difference (since it is just a "bit perfect" data), unless they alter it. Other people can have different results with different programs when they have different (no network) connection, like S/Pdif (where timing plays important role). In such case playback program, speed of computer, amount of memory or playback from memory can make audible difference.
I keep my CDs in ALAC format. It save HD space and it is (I believe) format of data being sent over Wi-Fi.

The only negative side of Itunes is interface. I created "Smart Playlists" for each genre. It resulted in much better view with matrix of thumbnails on the page. Perhaps there is a way to do this without going to "Smart Playlists", but I couldn’t find it.