Got a Node 2i, what's next?

So, I admit that I'm not much of a digital guy.  I ordered an Node 2i for the main HT system mostly for Amazon HD.  Much better than roku --> Denon AVR-X3600.  I liked it so much I ordered another for my previously all analog 2 channel system.

It's not bad, and convenient. Not even close to vinyl on the same release and level matched recordings, but then again, I didn't expect it to be.  I keep reading about how you can easily improve the sound by adding in an external DAC.  Here's where I get confused.

I don't want to spend a lot on a DAC, because at best it's a secondary source.  I'd feel comfortable in the $500 - $1000 range, but I'm really confused over the options and how they relate to sound quality.

First, r/2r vs I guess delta sigma?  What are the sonic advantages of either, there are widely differing opinions there.  I understand how each works from reading around, but how does it relate to sound quality?

Second, multibit vs whatever else.  Same basic questions, what are the basic sound characteristics of each?

Third, oversampling or no.

And lastly, what bitrate/bit depth is considered adequate?  24/192 seems to be standard but some dacs only have 24/128 over optical.  Will this make any difference real world with HD streaming?  I also have an old NAD cd player with coax digital out I might want to hook up for kicks.

I've researched three so far, the Denefrips Ares II, , the Schiit offerings below $1K, and the Cambridge Audio DacMagic 200M.  I would like to have balanced outputs to keep the digital circuitry as far away from the analog stuff as possible.

Thanks in advance for your answers.