Dated but still A rated DACs

Just picked up a used CALYX w. Linear power supply for use with Headphone setup (Mac .. CALYX .. Icon(headlamp) .. LCD 3)
Amazing performer.  
The CALYX replaced a Jeff Rowland Aeris
However I think you may have a problem locating one

Nice to see the nod for the ARC DAC 7 by @vdotman  +1

I'll second the Hegel HD12, and add the Classe DAC1

I have an "all digital source" music audio system and believe that DACs are the things that are being "most improved" these days.

For the last 3+ years I've been enjoying a PS Audio DirectStream DAC whose unique design (based on an FPGA chip, instead of an off-the-shelf DAC chipset) allows them to publish firmware updates (which seem to be available 1 or 2 times per year), which improve the performance of the DAC.

If the DirectStream DAC can't be had for the money you want to spend, they also offer a DirectStream Jr DAC, for about 2/3's the price of it's bigger brother.

PS Audio is a fantastic company to deal with.

Dangerous Music Convert-2. Breathtakingly realistic - impresses me with a never ending series of wow moments when listening to good recordings.  Built like a tank. Very responsive and helpful support if needed - they assisted with a couple of technical questions I had. Price: $2,499.