Is JRiver still the best software?

soundwise, yep by far

I have JRiver and Audirvana- prefer the sound on Audirvana

Thank you for the input, everybody.  It tracks with what I'd been advised before.  Went ahead and pulled the trigger earlier today, imported my library and gave it a brief try.

It has noticeably better sound quality than Apple Music, but doesn't knock me out.  The software is far more feature-loaded with much finer control and that makes it less user-friendly, too.  As a case in point, I still haven't figured out why only a Chesky HD sampler and a Linn 24 bit Christmas download have their metadata and album names.  Several searches haven't pointed me in the right direction yet, so I'll have to keep trying.

The biggest disappointment turns out to be that it apparently can't control the computer MIDI hardware output settings automatically in real time to match native resolution of the source material.  To change from Red Book to 32 bit 192 kHz for example, I have to reset the MIDI output manually and restart the computer to save the setting.  

I was originally given to understand that was something that the software could do based on input to a posting here about the same isuue with iTunes back in 2014 or so.  A deep-ish dive into the JRiver support forums indicates it hasn't existed, if it ever did, since ~2016.

Worse, the MacBook MIDI does not upscale well; things like vocal harmonies get very harsh.  Downscaling works somewhat better although it sounds artificial.  That means a noticeable playback inconvenience remains.

So, if anyone knows how to address the MIDI control concern or has a tip about the weird metadata result, I'll appreciate your input.  Thanks again!

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.

@sandstone I appreciate the input - gave me the trail of breadcrumbs I needed to sort things out.

It wasn’t actually quite that simple; had to uninstall and reinstall JRiver before I was able to bypass the MIDI and get the settings changes to work. Tested it briefly this morning and verified files run in native resolution. FWIW, the C50 DAC doesn’t upconvert, just automatically adjusts to incoming bit depth and frequency.

Still haven’t been able to obtain the metadata; JRiver doesn’t seem to know where to find it. Maybe I just have to leave it running the search function for a few hours. Haven’t spent that much time on it and it’s not a huge priority anyway.

Thanks again!