My experience is with the Node. The built in DAC is decent, but I use a MDHT Orchid with excellent results.
This is exactly what I did and the sound is glorious. A separate DAC is necessary, and I like the R2R approach a lot. In your price range, another DAC like this that people favor is the Border Patrol and the Audio G-D. Also popular is the Black Ice DAC. These are things I've gathered by reading about them -- I have not heard them. So, FWIW.