Load the FLAC into Spek or Audacity. Look for a sharp cut-off at 22.05 kHz. That is the true CDDA standard. If you see a hard cut at 16 kHz, it is a transcode (a 128kbps MP3 wrapped in a FLAC costume).

4 Non Blondes - "What's Up?" CD Maxi-Single (CDM) released in

As a 90s alternative rock fan, I’ve put together a blog post for you that dives into the significance of that specific 1993 CD Maxi (CDM) release and why audiophiles hunt for it in FLAC format today.

The 1993 CDM transfer to FLAC preserves the —specifically the difference between the quiet, spoken verses and the thunderous chorus. Modern remasters have crushed this range to zero. A genuine FLAC rip of the 1993 disc has a DR (Dynamic Range) value of 12 or 13, which is heavenly.