I'm looking at getting some sort of firewire digital audio interface so I can run things like Mainstage, Amplitube, etc with my bass onto my MacBook. In particular, I'm looking at a Focusrite Saffire. I've noticed that the LE version is cheaper, which is appealing, but it doesn't have a built in DSP. Do I want the built-in DSP? Or do things work better without it? Or is there another interface I should be looking at?