Fatigue is directly related to distortion.
I would check a few things. First, snug up the fasteners of your drivers and tweeters. Dont overtighten. Second, consider your room's interaction with you and your loudspeakers. What is the environment like? Have you moved things around or introduced furniture that is resonating or causing unnatural focused energy on a narrow band? Third, if your playback setup is a computer have you ruled out an update or setting somewhere that is causing dynamic compression?
Sidenote
Ripping to Flac will not improve upon a CD if that is your understanding. It is just a more efficient storage container. It is a convenience to have your files on a NAS server, but since Spotify or Tidal offer excellent sound quality, ripping CDs isnt worth the headache anymore.
$10 a month. No brainer.
