Best EXTERNAL DAC suggestions

I have to see/hear if an EXTERNAL DAC will now be order?

First, congrats on the new pre!  I’m sure you’re gonna hear very significant improvements, and please let us know what you think once you getter burned in a bit.  
That said, significant further improvements await ridding yourself of the Node’s onboard DAC especially now that you’ve got a good preamp that’ll more fully expose the benefits of a good separate DAC.  I think you’ve got a lot to look forward to in the future, and congrats again on the new pre.

Tubed R2R DAC.........The One and Only...............drum roll please...................................................................Audio Mirror Toubadour IV-SE.............Everyone that owns this unit is Gaga over it. You will be too.

If you are looking for warmth and soundstage, put some NOS Mullard  12au7 tubes in that Rogue. I had a Rogue Pharaoh integrated and replaced the stock JJ tubes with the Mullards. This took the Pharaoh to another level. Warmth and 3D stage in spades! Not cheap, a pair will set you back approx. $140, but well worth the investment. 

@mr_m I used Brimar CV4003 from upscale audio in the RP-1. I think these and your mullards are essentially the same tubes. Very nice improvement but the Gold Lions aren’t too far behind

I have no experience with Gold Lion tubes, but I'm sure they are great tubes based on reputation. 

I think the CV 4003 tubes are military grade variants of the 12au7, but are essentially the same.