DACs with a budget of $800

The NAD c165Bee is actually a very good preamp. It doesn't have the somewhat exaggerated midrange glow of my tube preamp in my other system but its quite balanced top to bottom with good soundstage and air. Your tube Blue Circle might give you that added "air" especially on vocals but remember it has twice as much output voltage; 20V vs. 10V, so keep that in mind when pairing it with your amp.  

@Kalali
Yes, the little budget pre has served me well and I agree with you about tonal balance. However, I think that my room presents some problems with the speakers I use most (Spatial Hologram). My room its 12 ft x 19 feet and my front wall is the long wall due to room set up/floor plan of my home. I get great separation left to right and good height, I just have almost zero depth. Sure tweaking the speaker placement is a big deal, but even when the speakers are optimized in my room the sound stage really 2 dimensional and very forward. I have never had any tube gear before and am excited to see what it can do for a three dimensional sound stage. 

I will send out updates and impressions after I get it running next week.

Oh and BTW I will be moving the NAD 165 to the bedroom system (Maggie MMGs. stereo REL t-7's, and an anthem MCA 20 for power). 

Schiit used 

@erik_squires 
yes, +1 for the Schiit Gungnir Multiibit, can be bought used now. 
and remember that the Schiit price on their website is about 1/2 the price that it would be if it were sold in brick and mortar buildings-

Schiit sells direct to you, no middleman.