The issue I see with iTalk and similar iPod apps is that the iPod has no line-level input, so you'd have to use one of the earbud/microphone combinations or an external microphone like
this one which will be limited as to quality. There are some other options
here. But if you want pro quality, and particularly want to tap straight off of a mixing console, a device like the Alesis is going to be necessary, though there may be something less expensive that I can't find.
If a microphone works for you, then iTalk might be fine. There's a freeware version of iTalk, iTalk Lite, you can try, to see if it will do the job. It doesn't have the advanced playback controls and has a limit of 2MB per recording, but it should allow you to test it out.
Voxie is another possibility.
Regards.