Never before has Apogee quality been delivered at such a low price point. It's important to understand that there is no product out there that will compare sonically to Duet, short of spending thousands more (i.e. Ensemble). To ensure the headphone output achieved the quality we sought, we had to have the same signal path to both the headphone output and main output. To include a separate D/A for the headphone out would have increased the cost significantly. That being said, one of the coolest features of Core Audio is the ability to aggregate multiple devices into a single device. This is possible with the built-in audio I/O of the Mac. So for cue mixes, aggregate Duet and the built-in output and you're good to go.