this is a little off topic but might help, the old ZX Spectrum computers used a similar system to recieve information, they were designed to use any tape deck that you had available rather than a model specific deck and took in the audio signal and converted it into binary code, schematics for the circutry are appairently online and as it is more than twenty years old any patents have worn off.

maybe looking into this might help with some of the problems the peachy is having and could solve the sound card problems.

to get a better idea of what I am talking about check out The Ben Heck Show episode he released on friday.