WaveShop is a fast and lightweight audio editor. The program is bit-perfect, meaning uncompressed audio samples aren't altered unless they need to be; editing a portion of an audio file only affects that portion and the rest of the file remains untouched. Cut and pasted audio blocks won't modify their
contents. This is especially useful for patching a finished master without corrupting its dither. Other features include unlimited undo, peak and RMS analysis, normalizing, fading, audio generation, and more.
http://waveshop.sourceforge.net/index.html