metaflac --show-tag=REPLAYGAIN_TRACK_GAIN *.flac

Choose "Album Gain" if you want to preserve the intentional volume differences between tracks on a single record, or "Track Gain" for a shuffled playlist experience. 2. LoudnessScanner (Cross-Platform)

Depending on your technical comfort level, there are several ways to apply these fixes. 1. foobar2000 (The Pro Choice) This is the most powerful tool for Windows users. Select your tracks. Right-click -> .