Here is an interesting new one from Antelope to be shown in Munich next month.
Antelope Rubicon Atomic AD/DA Preamp
http://antelopeaudio.com/en/products/Rubicon-Atomic-AD-DA-Preamp
Rubicon is the first DAC to integrate a Rubidium atomic clock, which is 100,000 times more stable than a traditional crystal oscillator. Coupled with Antelope’s 64-bit Accoustically Focused Clocking technology, the Rubidium achieves a breakthrough in jitter managment, improving the sound quality in an unprecedented way.