Seeking Advice on NOS DAC

Thanks, everybody. I should have mentioned that I auditioned the Schiit “Gumby” and it sounded a bit too aggressive in my system. Excellent dynamics and soundstaging, but my system is very revealing and it wasn't what I was looking for.
  I've owned a Chord with FPGA and found it very smooth, so the Exogal Comet Plus is on my list. The FPGA that reshapes the waveform is a major advance in DAC technology.

Because of the low Input Sensitivity on my tube amp (1V), I'm limited to a DAC with good volume control or one with low output voltage such as the Metrum Acoustics Hex.

And thanks, David. I'll check out the Darko DAC index. I like his reviews.

Thanks, @jond . I will certainly start reading about this DAC.

I don't have a lot of experience with DAC's but recently purchased an audio alchemy DDP-1 with the optional power supply. It's exceptional with redbooks, which is about all I own. The preamp section itself is also very good (it replaced a Melos 222 & betters it in every way) & has analog inputs. Audio Advisor is selling these currently for $1500. If you have time, check out the review from absolute sound.  

Low- I haven't heard the Border Patrol, but it checks the right boxes, tube in the power supply and the more robust version with one output of your choice is below your budget. I was also looking at some of the Audio Note Kits, but the Border Patrol may do the trick. No way to listen to it, though, unless you find an owner. 

Thanks guys, both DAC's look interesting. And @whart  , the Border Patrol does "check the right boxes."

@jond ... Enjoy the Music gave the DAC2.1 Signature a  phenomenal review. It looks like everything I could ask for in a DAC.
My only issue is the review is from 2005. So I'll ask you, what type of questions should I ask the seller/dealer?
Condition of caps and the tube circuits come to mind. Also, there is no USB input.