For the monitoring I would assume that you are talking about during recording, in which case it would be hardware monitoring within the Onyx, completely a seperate thing from hearing what it is playing in your software, which would explain why it works, but playback doesnt. Sooo... What kind of levels are you showing with your meters inside of your program, and during playback what is it showing on the onyx as far as monitoring volume. Also just to make sure, you do have the onyx set to send the firewire signal to the control room/phones, right (this is what I monitor off of obviously, and how I would set it up)? To really know any more than that I would need to know your signal chain, what is hooked up where, and what software you are working with, as well as what the meters are doing during playback.