"Bridge Over Trouble Water" sounds artificial

Sounds like you are now able to “hear into the mix” better now than before.  The pros and cons of a highly resolving system.  

While I agree with crn3371, what you might be hearing is a poor mix of the Simon&Garfunkel track.  I remember that back in the day there was a lot of criticism Of S&G mixes, that they were “overproduced”.  Since I was a teenager at the time with my parents system that cost around $29, I couldn’t have said, and I only listen to Classical now, but I did hear some S&G tracks at a show a few years back and my reaction (to the recording, not the music) was “Yuck!”

So many versions with differing dynamic range which is yours. (click on each "album" to find out)
I usually find the later ones and most streamed/downloaded not only more compressed but also much louder mean level recorded.
http://dr.loudness-war.info/album/list?artist=Simon+%26+Garfunkel&album=Bridge+Over+Troubled+Water

Cheers George

Key quote:

With my upgraded equipment the hi resolution audio sounds very synthetic, with one track on top of another, not like real music at all. 

Key phrase: "high resolution audio".
Simple hack that will serve you well in life: whenever one simple word is replaced with a whole bunch of syllables, run. In this case the word "record" is replaced with "high resolution audio." Where in your life have you ever heard anyone describe the sound of a record as "high resolution audio"? Its a record. It sounds like music. You're listening to a file. Expecting a file to sound like music is... oh wait, what? Digital forum? 

Nevermind. Sorry. Probably went right over your heads. Forget I said a thing. Carry on as you were.

Done something wrong? Not at all!

What have you upgraded recently?
It seems likely that your changes have resulted in a more revealing combination of equipment which sharply illustrates deficiencies in production, miking, mixing techniques, and possibly, listening room acoustics.  
Recently I upgraded my primary source to digital streaming, my amplification to a newish brand integrated amp with DAC onboard that has been highly praised for its sound quality, and finally, my speakers to Spatial Audio M5 Sapphires.

The changes were done one at a time with one or more weeks between each piece being added. This allowed a fairly long period to discern the difference in sound quality that each     swap made.
To be brief, upgrading the amp and then the source while using my old speakers moved me to tears when listening to choral and classical music that I have known (and performed) for decades. 
Adding the M5 Sapphires Increased my pleasure in the classical and choral recordings BUT a surprising number of rock, c&w, jazz and folk recordings became decidedly LESS SATISFYING TO LISTEN TO.  

The problem? They sounded ‘synthetic’!  Doubled voice tracks with added reverb and peaked up frequency balance were now much more obvious.  Individual tracks with distortion added stood out clearly with the much more transparent M5Sapphires. 
I’ve rambled on too long so I’ll close by saying that one of the costs of upgrading to ever better, more revealing gear might well be diminished satisfaction from some recordings in your collection.