Look.. my basic philosophy is K.I.S.S. (keep it simple, Sadie

).
I mean, you can hook up any audio network you want to... knock yourself out. But before you make things way more complicated than they need to be, ask yourself.. why not K.I.S.S.?
For now, just to get started with Ms Pinky, here's what I recommend for you:
a) Stick with the FS2 Amp. Plug your turntables directly into the FS2, plug the outputs of the FS2 to the line ins on your mixer.
b) Start with Ms Pinky's "Maxi-Patch_AO" program for OSX, Universal Binary. It will run excellently on your Macbook. Inside the Maxi-Patch program, select the FS2 Amp as your audio device. It'll be sooooo easy.
Then put those lovely pink records on your turntables, load an .MP3 of your favorite song... and scratch away at it for a while. Be sure to read the "Quick_Start.pdf" guide that comes inside the Maxi-Patch download folder. Let that be your guide.
Later on, once you've mastered the basics of Ms Pinky's Maxi-Patch_AO program, then you'll be ready to experiment with more advanced configurations and string audio cables all over your pad and have 13 computers and 45 audio devices all running simultaneously in a huge feedback loop, if that's what you want to do
Just for now, please K.I.S.S.!