Ayre QB-9 DSD or Codex?

The Ayre Codex DAC is in current production while the Ayre QB-9 DSD DAC is not. 

The sound quality of my Codex DAC is excellent and I suggest you give it listen. I use my Codex DAC as a DAC and its sound quality is excellent.  I also used the Codex DAC as a pre-amp with great results.

i am not  familar with the Esoteric D-07x unit.   Several years ago I had the Ayre QB-9 DSD DAC and believe the Codex DAC sounds better but everyone has a different opinion on this. 

I suggest you audition the Ayre Codex DAC.  

Please see the link below for an Ayre Codex DAC listed for sale on Audiogon:

https://www.audiogon.com/listings/da-converters-excellent-condition-great-sounding-dac-preamp-2017-1...

I second the Codex.
Though I haven't heard the QB-9, I am hesitant to spend a lot on a DAC, as technology changes so rapidly with this item.
The nice thing about Ayre is that they offer upgrades.
In my opinion, the Ayre Codex is on par with the Schiit Yggy, with the Ayre slightly better. 
YMMV
Bob

I also agree that a Codex is a great sounding, terrific value DAC. Comparing it with a QB-9 I thought it sounded less analytical and warmer, without sounding overly euphonic.

Other thing I like about the Codex is that I can run both my Aurender and CD transport. The QB-9 has one input.

I can't believe someone hasn't jumped on the Codex for $1200 in the classified adds. I bought a near mint condition Codex at about the same price here and could not be happier with my purchase. Makes the Bluesound Node 2 sound like a giant killer. Especially in balanced mode.

I’m trying to jump on one but the seller didn’t reply back to me yet...

Also, I don’t run balanced on my setup, so I don’t know if I would get the full benefits of the Codex.

After doing a bit more research I'm not also looking at the Mytek Brooklyn+ which supports MQA, comes in around $2k new and has a 30 day in-home trial.

I know the QB-9 fairly well and enjoyed it, but MQA intrigues me and I am a Tidal user.

DAC technology moves so quickly it's really difficult to know when to jump in.

Thanks for all the feedback so far.