ADC data in .wav format

Hello,

I have a cheap Chinese sound chip I am interfacing to. The problem is I don't have any I/O left and the only thing that is available is DAC output port. I have recorded a capture of 2400bps serial data in a sound file via PC mic port. The only problem is the capacitive coupling which results does not give me saturation to DC. I have to manipulate the sound file to saturate the levels to get my serial stream not to mention crop and trim..etc.

Is there a USB ADC with dc coupling that will allow me to save my data as a .wav format? I have 255 commands that I need my pic to recognise. I have 1 byte that works so far...254 more seems such a waste of time if there is a smarter way to get the serial data into a sound file without sound forge audio manipulation.

I would appreciate your help.

Best Regards,
Nick