You can get good sound from digital if you use uncompressed file formats. The problem with WAV files is there is no Metadata (track name etc.). FLAC is uncompressed and maintains the Metadata so I would recommend FLAC. Use Dbpoweramp or Exact Audio Copy for a PC and rip CD's to the hard drive. If you are taking CD's and making MP3 files you will easily hear a difference in quality because MP3's are compressed.
My bet is that your system is ripping MP3's to your hard drive. Ouch! Those are compressed files and they remove lots of sound from the file. It's like the difference between cartoons on cards that you flip so that the characters appear to move (and your brain fills in the gaps) and real life.
Having said that: Nothing beats perfect vinyl from a great phono, it's the ultimate in an uncompressed file (it's beyond a high definition CD file), but there is a place for Digital. I remember the first Audiophile I ran into as a kid. He showed us his system and had a reel to reel tape player. He recorded his albums and listened to the reel to reel casually, but when it was time for a real listen the albums came out. He explained that by doing that he preserved the integrity of the albums. Additionally, iIt has some other advantages: no pops, clicks or scratches etc. The ability to skip from completely different songs and/or albums easily.
I'm an old fart too and have had to educate myself on this stuff - I still need more work.
BTW on another thread you asked about the Oppo. It's a good player. An incredible value for the money and nearly bullet-proof playing anything you throw at it. Some high end players can be a bit picky.
Hope this helps. Email me in Audiogon if you need help - I'm not a dealer and I don't have anything to sell. Just trying to help another "old guy."