I’ve heard both. Although, some say that the QB-9 DSD sounds better, personally I think the Codex sounds as good if not better especially with a few upgrades like the power cable. I own the Codex and I’m very happy with the performance. Like all Ayre components though, they sound the best fully balanced. Is your system single ended or balanced? If your running a single ended system, I would also consider other DACs . With the Codex, I noticed that balanced or not balanced makes a significant difference in SQ. Don't get me wrong the RCAs sound great, they don't compare to the balanced outputs.