Just picked up a Focusrite Scarlett 2i2 interface for use with my MacBook. I set it up as the input and output device, patched track 1 in the session to be input 1, and when I hit the R button to arm the track, I don't get anything in my headphones, but do get an audio level in Audition. It records and plays back audio just fine, but I have no ability to monitor live. I'm not sure if it's a setting I have improperly configured, or whether I have a faulty unit. Please help!
Here's the trick. It helps to press the "I" button to monitor the input...oops
Only doing it that way is likely to produce a lot of latency in what you are hearing of the recording input. This may not matter but if you are trying to record new live played instrument tracks alongside already recorded ones you are likely to run into problems. You should really use the 'Zero latency' monitoring switch built in to the Focusrite.
When recording vocals it is often prefered to have some reverb in the voice and the direct monitoring option won't let that happen. Latency is a possible concern if a lot of processing is going on as you record, but it can be reduced or eliminated with proper buffer and bitrate settings.