Looking for best streamer without DAC under $3500

I have the LUMIN A1 which has an external power supply. It’s extremely quiet and has a very dynamic sound. The chassis is solid billet aluminum and gas pretty substantial weight to it. The app interface is pretty good and there’s occasional updates that automatically come via the network. I think the built in DAC is very good although you said you would prefer an outboard a DAC so you could get Lumins streamer only and use your DAC and I’m sure it will sound great.  I think it sounds as good as my analog setup but it is different sounding. 
Rick

I don’t think anyone mentioned the SoTM SMS200 Ultra Neo with an outboard power supply. That’s what I use into a Chord Qutest via USB.
It’s not too expensive ($1200), works and sounds great and is Roon Ready plus a large number of other connection options included.
Unlike Lumin or Auraiic it doesn’t come with a player software, just ways to connect to all the favorite kinds of players over the network.

It’s basically a small, silent Linux computer optimized for audio that becomes part of a wired Ethernet network and outputs clean USB with a solid clock. The OS is on an SD card but you don’t really have to do much but select which player software you want to use.

Lumin U1 Mini is hard to beat for the price.

Stereophile reviewed a couple of servers in the two most recent issues, Innous Statement and Wolf something or other, with the cheapest being about $10,000. Both of them were compared to the Roon Nucleus+ with an upgraded power supply - total cost about $3400. The Roon more than held its own.

You can't output to an external DAC with the D2 correct? The T2 has the ability, but the D2 has to stay in the box?