MP3Gain Express is a port of MP3Gain and AACGain to macOS. It allows you to analyze or apply volume gain to a list of MP3 or AAC files. Anyone who has used the Windows UI for MP3Gain should find this one familiar, as it was designed to look similar to that version. It's easy to use. Simply select the files you want to increase or decrease the volume of, enter the desired loudness, and click Apply
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