Budget External DAC Recommendations

I just upgraded my Audioengine B1 Bluethooth receiver (using iTunes) to a Bluesound Node 2i (streaming Tidal Hifi) and the increase in sound quality is shocking.  It has me wondering if I can make another incremental increase in SQ by purchasing an external DAC.  Will a $400 - $500 DAC substantially best the DAC in the Bluesound Node 2i?

I am looking at the used market and have narrowed my choices down to (in no particular order):

- Chord Mojo
- Benchmark DAC-1
- PS Audio Digital Link III
- Denafrips Ares II

Which is the best? What else should I be considering? Also, for those who have heard the Node 2i's DAC, how does the DAC you recommend change the sound quality?

My system includes the Node 2i, Rogue Cronus Magnum and Totem Hawk speakers.

Thanks for any suggestions!
I have the Vault2 and upgraded to an outboard DAC to one of  the higher-end PS Audio DACs. Well worth it. I would say in my opinion, spending $4-500 might get you a little improvement, as again, the Bluesound DAC isn't bad. But I'd suggest holding off until you can get to at least the $1500-2000 range to really make a difference. I owned the Totem Rainmakers and liked them a lot, with your Rogue amp, you'll hear a big difference between a $500 and $2K DAC. Going from Bluesound to $500, not so much in my opinion.
I would continue to use the internal DAC and save up money for a more significant upgrade. 
I'm looking into Audio-gd R2R-1!
RME ADI-2 DAC, brand new.

Best bang for the buck dac. Worth saving up your money for this. Or, get a new Ares 2 dac.