This is less relevant now considering the "sale" and large price cuts PS Audio has on their dacs however....I originally purchased a Jr. and noticed before the last OS upgrade a weird pulsing artifact with the Jr once the volume was at a certain level (I think it was at "75"). Extremely weird. I called PS Audio and (Jason?) offered to upgrade me at no charge to the Sr. I’m really happy with the DS dac. For me its the smoothest, most analog dac I personally have heard and that includes some of the r2r dacs like the Metrum units. I purchased the Jr at a significant discount...not directly from PS Audio. All they required was that I return the Jr and they shipped me a Sr at no charge. I was impressed. Go for the PS Audio!