I agree with everything Jprice has said. I usually go back and forth between 512 and 768, but mostly listen at 768. I believe the "D" value is for the digital outputs. I might look for another digital source in the future, but nothing comes to mind that is vastly better than the 306 at this point. I considered the Ayre C5XE but settled on the Cary. I listened to the Esoteric X-01 in my system and preferred the Cary.
The build quality on the 306 is truly impressive as well.
The build quality on the 306 is truly impressive as well.