

Almost no one can, or have equipment that can make the difference. That being said, the difference between an old mp3 and a new one is sometimes noticeable at the same bitrate. The encoding algorithm has improved a quite lot since the late 90s. I bet a lot of people who say they hear the difference think about those old encodes.
I keep flacs as a master format that I make new encodes from when I want it on my phone and such though.
It was kind of easy for me, as I already used Plex for video, but Plexamp has been such an amazing experience for rediscovering my own music. The radios, sonic matching and DJ algorithms are fantastic. I’m sure there’s other similar solutions, but it’s really worth investing in, imho. There’s currently a lot to be desired with the library management, but the player experience is worth the downsides for me.