Are you talking sample rate (as in 64,000 kHz)? That's definitely a wierd number!
In theoretical terms, 64K s/r has been discussed as an "ideal" compromise between bandwidth needed for our ears and anti-imaging filters and efficient transport, but I'm unaware of any commercial systems using it in the field.
Are you sure it's not a 32kHz s/r, saved with 64 bit native (d/p) words?
Interesting...
-d-