After giving up my Ubuntu laptop recently, I’ve been back on OS X¹ as my primary computer. And it’s been incredibly hard to find a decent ReplayGain scanner tool (to replace my old foobar-on-Wine setup) until I discovered the excellent ReplayGain Scan Utility for Mac OS X by Martin Scott in a Blogger corner of the interweb.
The program does one thing and does it well. Just drag your files and drop it to the app, and it’ll scan and save album gain metadata. Works like a charm on FLAC, M4A, and MP3 files. (Doesn’t work on Lossless AAC if that’s your jam.) If you’re on Catalina, you need the recently updated Version 0.3.
¹Turns out that since 2016, one does not say ‘OS X’.