this site is always interesting to check.
http://www.fmjsoft.com/awframe.html
not sure how up to date the formats are but it looks like there are two types of .WAV file formats oddly enough.
on that .F64 it seems to imply it is mono as of the standard. Pyramix have probably custom extended the format. They might not want to give you some bad news that it is a custom format. not sure. There maybe some way to extract that data but I suppose you would need a 64 bit architecture machine to do that because of the memory. and even then. no certainty.
QUOTE:
.F32/.F64 - Floating point raw 32/64-bit IEEE data
Notes:
If you try to read data that actually aren't IEEE floating point as .F32/.F64,files, then the application may hang with an invalid floating point exception error.
Features:
32 / 64-bits floats, mono.
Supported by:
Awave Studio (read + write).
Awave Audio (read + write).
ACDR (write only).