Thanks folks. These are interesting suggestions and have been reading up on them. It turns out there are some darker issues was not even aware of regarding sound output from Apple Music.
a) apparently Music does not automatically update the bitrate of the output to the bitrate of the track. Unbelievably this has to be done manually in the AUDIO MIDI SETUP utility. Since nobody does this the recommended solution is to use iOS !!
discussions.apple.com
b) Since most of the time there is going to be a mismatch between track played and the Audio Midi Setup, the Mac will upsample or downsample the data as necessary to get the manually set output. This is TOTALLY NUTS.
Am going to have to wander into some Hifi / Stereophile joint and see what they are saying. Perhaps Apple will be reviewing this in time for the launch of the Classical app derived from the Primephonic acquisition? Like seriously, I thought / assumed apple was hot on this media processing stuff.