WaveShop (64-bit)

From CKCI: WaveShop (64-bit) is a free and open-source audio editor. Editing a portion of an audio file only affects that portion and the rest of the file is untouched. Blocks of audio can be cut and pasted without changing their contents at all. This is especially useful for patching a finished master without corrupting its dither. Features include bit-perfect: samples aren't changed needlessly, all processing is done in memory, 64-bit version can edit files exceeding 2GB, clipboard: copy, cut, paste, insert, or delete, unlimited undo, normalize and/or fix DC offset, amplify (boost or attenuate), fade in, out, or custom, linear or logarithmic, peak statistics, RMS statistics with histogram, reversal and inversion, find clipping with detailed report, extract channels to mono files, insert, delete, or swap channels, change audio format, generate audio w/ envelopes and modulation, edit surround speaker assignments, find zero crossing, Multiple Document Interface (MDI), multithreaded processing, and playback via DirectSound.