Node2i + Qutest or Yggy or Codex or something else

Audioadvisor.com has the Auralic Altair on sale for 1699.00. Very good dac and much better streamer than your using now. If not that, a used Auralic Vega is a great match with the node 2i. They are a steal at the 13-1500 used price range

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.