Adobe Soundbooth is an audio editor which let you modify and power up your audio files.
It's a simple as add the file to a edit list and choose what we want to add or do on the file.
Since the first time you run Adobe Soundbooth you will be able to merge, divide, add silences, fades up or down, tones, add effects, mix your favorite songs,...
If you think about the quality of the products offered by Adobe, such as Flash or Photoshop, you will realize that the features offered by Adobe Soundbooth are really good.
30 day trial period