Maybe a CD with the old song originally recorded with audio equipment and originally released on vinyl and later re-released on CD as it is i.e. without any remix etc, could be seen as the "uncompressed" version of an old song (but I don't know).

It could be ripped as a WAV file with Windows Media Player (legacy).
To make a compressed MP3 version to use as comparison maybe one could use Audacity and select a suitable compression level (unless already available on YT