Amplifying does't work in batch process. I use wavepad master version 5.5.4. Step 1 : Add folder work1, some m4a files there Step 2 : Add command "amplify" with gain 12% Step 3 : Choose Same type file and output folder work2 Output files were created in work2, however those were not amplified, same as original files in work1. I also tried 'Echo" effect command in same way. That works correctly.