Are you firing up PodFarm independently? You can monitor from PodFarm standalone and shut off echo within Sonar.
{edit} Another thing I've done is create a separate bus that I name "headphones" that bypasses the Master. Then send the track I'm recording to the "headphones" bus and turn down the master.
I just recently learned about the Solo Dim feature though, so now I'm thinking I'll just click the DIM button, then solo the track to record to it; so the rest of the tracks are still audible but not as loud.