I think the problem is that the FTPro wants big endian samples (which
is a tad unusual, but not 'bad') and the other tools want to send it
the native machine endianness (always little endian on intel
processors).
ALSA will be able to play if you use a plug: device. Postfish is old,
so it's OSS only. It's a little weird that the ALSA OSS emulation
won't accept little endian playback through the OSS device and just do
the swapping.
Monty