Vquestor, now you are getting into areas I am not as familiar with. My Steinberg VSL2020 has the following:
ADAT 2 IN/OUT
Analog 1 IN/OUT
In general, I will take a similar approach and try to keep everything software based including all the Analog In/Out mixing. As a result I will only need one Analog Out to my mixer. To make quick changes during live performances I would setup all my instruments, harmonizers, auto accompaniment, etc. in advance and switch them from my keyboard via channel changes, volume changes or style part changes. In addition, your soundcard comes with a mixer. Finally, I use a Yamaha volume pedal to vary the overall volume of my external Yamaha rackmounted mixer.
I agree, your approach would be better for live performances.
Firewire performs very well from what I have heard on other forums. Firewire works very well for fast Hard Drives (7200 rpm with 8 mb Cache). M-Audio produces high quality sound cards. So you should see very good performance indeed. My soundcard also uses unbalanced analog In/Out. While balanced would give you better shielding and performance, unbalanced will do very well.
Just curious, why would you go Firewire if you have PCI slot?
There are some advantages to running more than one soundcard. It gives you more opportunities to run standalone soft synths.
[This message has been edited by Frank L. Rosenthal (edited 09-01-2003).]