Click “Normalize”. The software scans each file, calculates required gain, and applies the change without re-encoding (lossless for MP3 gain adjustments via header tags, or full decode/recode for other formats).
No tool is perfect. Be aware of:
Overwrite original or save to a new folder. ID3 tags, album art, and file dates can be preserved. Sound Normalizer v8.7 Multilingual Portable -FT...