"AU" audio file format can contain the data in the 32-bit or 64-bit float encoding. JavaSound supports only "32-bit IEEE floating point" encoding for AU file format, it would be good to support the "64-bit IEEE floating point" as well.
When support of AU was added to the JDK(around JDK 1.3) the float encoding was not supported. But in JDK 7 the 32-bit and 64-bit float encoding were added for WAV format, and it can be reused by the AU file readers/writers.
This is the request to accept "64-bit IEEE floating point" encoding in the AU file readers/writers.
https://en.wikipedia.org/wiki/Au_file_format encoding 7 = 64-bit IEEE floating point