hi,
i've got a machine with the same audio chip (yet maybe a slightly different version)
I have really no idea and I think this somehow is strange behaviour and Pd /should/ work with the AC97 chip.
actually it does for me. but it only did so when run over alsa in my case - and even then i got loads of drop outs.
i think you should really try to get alsa running ... if the chip works in other alsa apps in duplex?
lg martin
attacksyour.net/pi