Considering Nagra Tube Dac with Power Supply or MSB Reference ?

Does anyone have any experience with the Nagra Classic Tube Dac and the Power Supply or MSB Reference Dac?

I demoed the MSB Reference Dac in home and loved it and have also heard good things about the Nagra. Looking for feedback if anyone has experience with both. 

Key Components in system are Audio Research Ref6SE preamp and Ref160S amplifier.  All cabling is Transparent Reference.  Speakers are Wilson Alexia with 2 S812 REL subs.