dac and streamer or seperates

I would recommend Aurender NH150 and Schiit Yggdrasil. Works well for me!

@vonhelmholtz 

saw a Bryston BDA 3 over on USAudio for $1.5K that might pair well with the Air Lens. Bring you in under $4K. 

The Krell DAC is not that bad (ES9028PRO Sabre) $1K option correct? and I can only imagine they wouldn’t slack on the implementation, check it out here where they compare it to a comparable priced external.

https://www.stereophile.com/content/krell-k-300i-integrated-amplifier-page-2

You might want to get a nice streamer and run it through there first. Then demo external  DACS 

I’ve just finished my journey down the same path as you’re heading now. I started with a modded Cambridge cxn v2, modded by ModWright. Excellent sound and the streaming end is absolutely seamless. I’ve never had a streaming glitch in over a year. 
I decided I wanted a little different sound and now have separates. I spent more on the dac, by a lot, and decided to go with the LUMIN u2 mini as the streamer. Great unit and it will sell quickly when I upgrade in the future. Definitely keep resale in mind when purchasing. I would spend the bulk of cash on the dac. I purchased the Rockna Wavedream and it’s a tremendous difference. Hard to tell how much the LUMIN added. Anyway, you can always spend a grand or so on a good streamer. Try to find a new model since improvements are coming fast and furious in that price range. 
Perhaps a Benchmark/LUMIN u2 mini would be perfect?

Definitely separates, but you can always start with a great streamer first and see if you are happy with your current DAC.....if not then upgrade. I a higher end streamer will definitely impress though