Are there any lossless compressors available specifically for digital audio ?

There certainly are. One proponent of Lossless Compression is Etree.org a music distribution hub but not for audio that has been compressed in a lossy fashion like MP3 or AAC but for audio that has been compressed in a lossless way. Etree.org uses the Shorten (.shn) audio compression format because it creates an exact clone of the original source.