Compressor 2 supports high resolution audio up to 64 bits per sample (floating point) and sample rates up to 192 kHz. If you have disk space or bandwidth limitations, you must compress your audio. Do note that audio takes up less disk space than video, so you won't need to compress it as much as video.
The most important components of audio codecs are sampling rates and bit depth. Sampling rate sets the sound quality; bit depth sets the dynamic range of the sound. QuickTime audio codecs allow you to set both the sampling rate and size of your source media file.