I received my Ayre Codex DAC today and changed the input source to USB and the output device to Pre-amp (goes direct to my power amplifiers). The unit was then installed in my main audio system and my first impression is out of the box, it sounds very good. As I noted above, I purchased 3 Ayre Myrtle wooden blocks ($15) and placed the Codex on its side (yes, it looks better in this position). It was interesting to see that the writing on the back of the DAC corresponds to the unit being on its side. The unit is very small but I had no problems connecting any of my cables.
As an experiment, the Codex DAC will stay in my main audio system for a while and will then be moved to my two channel home theatre system (original plan). As another experiment, I will move my Prism Sound Callia DAC to the main audio system to see how it sounds compared to my Bricasti M1 SE DAC. Today, I received instructions from Prism Sound to update the firmware on the Callia so that it will work okay with my Aurender N10.
The Ayre Codex DAC is an amazing small 3 pound box that sounds very good. I am anxious to break it in for improved sound. Based on results so far, the Ayre Codex DAC is recommended.