Awave Audio is a dedicated audio file format batch converter.

Main features:

• Does conversions from the about 90 audio file formats that it can read into any of the 60 or so audio file formats that it writes. See the complete list here.
• A 3-step procedure makes converting large numbers of audio files both fast and simple - handle one file as easily as a thousand.
• File size only limited by disk space and the limits of specific file formats.
• Handle everything from low sample rate speech up to "24/96" multi-channel audio and beyond. Up to 32-bit floating point precision is supported and there's no practical limits on the sample rate or the channel count.
• Several optional 'dithering techniques' are available (including professional noise dithering with highly accurate 'inverse F-weighted' noise shaping). This improves the perceived sound quality when decreasing the sample bit-depth (e.g. when going from 24-bit to 16-bit).
• Extremely high quality sample rate conversion (a.k.a. 'resampling'). Several options are available - the best ones have good enough S/N ratio to handle 24-bit audio with no perceptible artifacts.
• You can do optional effects processing using up to six 'DirectX plug-ins' as well as several built in functions.
• Normalization support including 'Replay gain' algorithm for psycho-acoustically corrected volume.
• Many types of meta-information are supported (a.k.a. 'text tags').
• You can also use it to record new audio clips and for ripping tracks from Audio CD's.