Best DAC for my system?

Talk to Tommy at the Digital Amplifier Company (DAC) the DAC DAC HS is exceptional. Contact him for a price he always has demos available. 
https://www.cherryamp.com/

Seems you have about 7.5k to 8k invested in your system so far... You owe it to your self to upgrade your source, streamer/dac... 2k to 2.5k seems about the right balance with your current kit... Benchmark and Chord are good suggestions... You might also look at Lumin... And some room tuning/treatment would not be a bad idea at this point if you have not already done so...

Kick the node and go straight to a Lumin D2 streaming DAC.
$1600 to $1800 used but your ears will thank you immensely.

Pro- Ject Pre Box S2 is  $400 at Music Direct with a 60 trial period. If you use Tidal it will do MQA if that matters to you. 

I have a node 2I and bought a used Benchmark DAC2 HGC from a member here and am very pleased. Just my 2 cents.