I read:
Linux 2.6.8. I've got an M-Audio Quattro attached, which seems to do pretty well with respect to data rates and channels using aplay.
good, so it works
From what it sounds like, I think there's an endian problem as the Pismo is big- and the Quattro is little-endian.
what kernel version are you using ? Maybe it's really an endianess bug in the driver (it has happened before with hdsp for example). Probably report this to alsa-user or alsa-dev aswell. But then aplay should also be affected.
I'm getting a "snd_pcm_hw_params_set_format: Invalid argument" response at the terminal, not in the PD message box.
you could try with alsa's oss emulation or jack and see if that helps.
HTH
x