Just download this file http://us2.un4seen.com/files/bassflac24.zip and extract the DLL to the Audio Comparer installation folder.
Typically it is c:\Program Files\AudioComparer\
And in a reply that it worked, I asked how to find out more codecs that AudioComparer may work with such as *.ape files. Bolide support staff said:
We are using bass.dll for "listening" to audio files. There are many
additional plugins for this DLL for different formats support, but
majority of them can't be distributed for free or can be distributed
with freeware only.
You can browse the plugins there: http://un4seen.com/bass.html#addons
Plugin for APE format is available at this address:
That makes AudioComparer work for my entire collection of codecs so I can see what I truly have duplicates of. It is easy to make mp3 files for portability then deleting them when no longer needed as long as you know you have the flac file from the original CD. Keep the CDs in a box so they don't get scratched because they will fall apart if they are old enough or used enough (the aluminum layer starts to flake off so you can see clear through the plastic).
Bolide enocuraged me to post their solutions to my questions but I see no section yet for AudioComparer. Possibly some moderator could move this in the future if people find the links useful. Good luck.