I loved what my Codex could do especially in its price range. I did have a friend with the QB-9 DSD and it was a slightly better DAC when we substituted it into my system. Smoother in presentation with a slightly more defined separation of instruments if I remember correctly. I ultimately upgraded to the Ayre QX-5/20 that was a substantial improvement in presentation across the board. I have not heard the QB-9 20 but the upgradability would make me lean toward the QB-9 if I was looking to purchase today. Enjoy it for a while then have the factory elevate it with the “20” upgrade. Ayre’s customer support was always excellent.