Node2i + Qutest or Yggy or Codex or something else

I have a completely different suggestion. Given the limitations of your listening area, consider a Lyngdorf 2170 with room correction. Its onboard DAC is very good as well so you can replace several components with one. Room correction is a big deal. 

Since the budget is $1800 here are options:
if you want clarity and realism and detail then the Schiit Yggy used is a good choice. Someone also mentioned the Gugnir. Also a good choice. Those are both multibit DACs. The Quetest is also good and in your price range. It has different filters and is adjustable to taste. A quality product FPGA DAC that is built like a tank. Another good DAC you can sometimes find used (I did) is the Mytek (a chip DAC) Brooklyn DAC+. I don’t have experience with the Codex. But these are all quality DAC and it’s a matter of taste. 

PC Audio,

Our club held a DAC Shootout last Saturday. 10 DACs involved.
The Schiit Yggy is $500 over your budget. Cutest is $100 over.
The majority of participants  chose the $800 Black Ice Glass FX DSD Wifi 
over almost all others including some at $6,000.  This was a blind test.
Take it for what it's worth and Good Luck !!
PS: Before I spent a penny I would install some early reflection absorbers where possible.

I upgraded from DAC in the Bluesound Vault2 to the Yiggy.  Fantastic!  You will love it.

@pc_audio - Here's another possibility. Looking at your system, based on the components you mentioned, you only have a single source - Node 2i. Since you are using the P5, which, based on experience with the unit in my system, is your weak link, you could buy a high quality DAC that also has a pre-amp or volume control built in. That way you could replace the DAC and pre-amp at the same time, with one box. Both replacing the pre-amp and adding a high quality DAC will likely provide significant improvements in SQ.

Not sure what current DACs have volume control. But I do know that the Mytek Liberty ($995) has digital volume control  and the Mytek Brooklyn DAC+ ($2195) has a built-in pre-amp.

This is just something else to consider if you want a boost in SQ within your budget (if you sell the P5, the Brooklyn would be in your budget if you used the funds from the P5).