Hi,
you give no numbers, no requirements
Also we have no idea what´s your understanding of "processing" means. Digital or analog? Simple low pass filtering .. or advanced voice recognition?
We don´t know what audio bandwidth you are talking, if you need real time processing..
If you don´t need real time processing you need to tell expected audio quality and length of audio time for data storage.
(Maybe you want to analyze birds chirping in a forest for a period of a whole month. We don´t know)
What is a "too big file size" for you? (If you have a RAM storage you may be limited to below 1MByte, if you have a harddisk you may have TeraBytes available)
The one that fits most to your (to us unknown) requirements.
Klaus