Is JRiver still the best software?

JRiver when properly set up, and with Redbook or HD sources, will definitely "knock you out" in comparison to Apple Music, if the rest of your system is even basically adequate.
Why are you resorting to a MIDI protocol?  This likely relies upon your computer hardware sound card for a conversion that you will want to entirely bypass.
I assume you are using Macbook's USB Out to Mcintosh 50 Digital In.  Go to Jriver Wiki and follow instructions for DACs with direct USB connection.  If your MaC DAC has a proprietary software driver, use it.  If not, under "Audio Output/Output Mode" select "Core Audio".   Then follow the other setup recommendations in the Wiki.
That should get you started and may also solve the data display problems you mentioned.

Your DAC appears to take the direct PCM digital stream of any resolution and upsamples it to 32/196, but the incoming preconversion bit/sample rates should be displayed on your screen.

You will also find that JRiver completely supports appropriately configured metadata.

 

@effischer ,

Glad that you're making progress and have experienced more of the capabilities of your excellent Mac C50!   Just a couple of questions/ suggestions:

Have you by chance downloaded and installed the software drivers and setup instructions from Mcintoshlabs.com?

Use a good USB cable (e.g. Belkin Gold) to connect  your computer to the USB port on C50. 

Then, look up
"USB Audio Windows Driver A Version 2.0 Installation and Operation Guide"

The driver install file is located right below the Guide.

Once this is installed, restart JRiver which will recognize and list it as a McIntosh-specific Asio driver option, that you should select.(Tools/Options/Audio Device).

This Centrance (third party) software is great stuff, btw. 
 

Then look up and follow

-- "McIntosh 32/192 PCM DAC, Preferred Settings to Play all File Types with JRiver Media Engine 20 using a Windows 7 or 8 Computer" --

This file is for the C52 but it steps you through what you also need for your C50.  

You should now have direct control over all the flexibility that the C50 DAC will allow.  Try selecting AUTO when given that option.

-----

As for metadata mgmt,  

Go to first principles...Try just ripping a single Flac file, store it locally on your computer, and use JRiver's Library management tools ( well documented on JRiver website) to define the file path to your file as a Library, then set that as your active library.  Save. Then it will persist when you log off.  You can then load as many other files into this path (Now a Library) as you wish. Or create and load other libraries. A Next step is to then use DLNA protocol to define any file set on your network and activate that as your Library for JRiver to manage.

Apologies if you are already beyond this level of detail.  Just let me add that Using  ASIO protocol and the USB asynchronous port is the recommended connection for your DAC, as it is with many other higher end DACs.

Hope this helps, good luck.

Sandstone

+1 @ho249 

For some, the better question is why anyone would pay $1-2 K for another overpriced black box, when with a basic understanding of how to optimize a computer for audio,  along with some very good software and and components, folks can and often do get the same or better results for a lot less treasure.  

But I get it.  Some would rather just spend the bucks and let somebody else do it for them.  YMMV.

I may have misread, but thought the OP asked us qn's concerning a specific task related to connecting two already owned components. - Not for advice on what new equipment to buy.