I use a Midisport 4x4 for controlling my synths, and a sapphire 24dsp FW card for input via my analog mixer (crappy but got it for free
. Main out from the mixer goes straight to the Sapphire`s main input, all synths are connected to the mixer on individual audio channels.
I have a Virus KB as masterkeyboard and I do all my midi recording/automation from that when needed.
The saffire also got 2 pre-inputs for i.e mics and guitars etc btw.
My Virus snow I usually use with the USB, when I get the sound i want I output it to the mixer and record it as any other of my synths. You get about half a second predelay which you have to manually fix after the recording is done though.
So if i get your question right, you need a Saffire soundcard (I recommend it, not to expensive and no issues at all this far), a midisport 4x4 (or 2x2 depending on your needs), and a analog / digital mixer.
A digital mixer can also feature a soundcard though, but they tend to cost a bit more than using an analog setup.
Hope this helps :P