Does anybody know a good audio-program, with which i can edit / change mp3- en wav-files?
Cool Edit (pro) or Soundforge have loads of functions and plugins, or do you only need basic cut & paste?
Goldwave is an excellent straight-forward audio editing tool and has many of the features of those expensive tools such as Cool Edit. Use the Lame plugin for MP3 support. Goldwave will decompress the MP3 as it opens it and once you are finished editing, you can save it back into MP3 or any other audio format.
If you wish to only edit an MP3 file but do not want to decompress or recompress it, use MP3DirectCut. This will let you cut and paste parts, adjust the volume, etc. without losing any quality due to decompression and recompression. I record audio streams off of satellite radio and MP3DirectCut does a good job in exporting selections into individual files.
Both tools will show the wave-form up and timing on the screen, which makes it very simple to precisely select the beginning and end of a song.
Goldwave which is shareware and the free LAME plugin are available here. MP3DirectCut which is freeware is available here. While the Goldwave shareware version is limited to 150 commands each time the software is run, I cannot see any other restrictions or expiration dates in it.