Tools of the Trade - Mac OSX

FLAC players for MacOSX...

FooBar 2000
Strange name, awesome music player. How a music player should be - small, modular, customizable and versatile. For Windows and Mac.
https://www.foobar2000.org/

X Lossless Decoder
http://tmkk.undo.jp/xld/index_e.html

Cog - an open source audio player for OS X.
The original developer of Cog - http://cogx.org/ - is no longer working on the project and a new team is now working on it. 
Information and Download:
https://cog.losno.co/

CD Ripper for MacOSX...

X Lossless Decoder
https://tmkk.undo.jp/xld/index_e.html

CUE files and file splitting...

Split album length 'CD Image' FLAC files to individual tracks using a CUE file.

X Lossless Decoder (XLD)
https://tmkk.undo.jp/xld/index_e.html

Audio Tag Editor

Add metadata to music files.

PICARD - Windows, Mac and Linux
https://picard.musicbrainz.org/
Download:
https://picard.musicbrainz.org/downloads/

Kid3 - Audio Tagger - Mac and Linux
https://kid3.kde.org/
Download:
https://kid3.kde.org/#download

Burn Audio CD...

Burn for MAC OSX
Burn - a simple approach to burning discs, but still offers a lot of advanced options.
https://burn-osx.sourceforge.net/Pages/English/home.html

Audio Format Conversion

xACT for OSX
xACT stands for X Audio Compression Toolkit for  Shorten, Monkey's Audio  Compressor, and FLAC. Used to Convert FLAC to WAV and other audio formats.
http://xact.scottcbrown.org/
Alternative Download:
https://www.macupdate.com/info.php/id/14246/xact

Audio Production and Editing

Audacity - A full featured Audio Editor
https://www.audacityteam.org/
Manual:
https://manual.audacityteam.org/
Downloads:
https://www.audacityteam.org/download/

CODEC Information

FLAC (Free Lossless Audio Codec)
Audio compressed with FLAC has no loss in quality.
https://xiph.org/flac/index.html
Tools for Mac OS X and Linux
https://xiph.org/flac/download.html