i think that there is still 2 versions of the dac
this is from the scott-nixon.com/dac.htm
"Simplifying the TubeDac and SaruDac+ choices. As of December 1st, both dacs will feature sinc filters that are switch-able in and out ! A small toggle on the rear adds the sinc filter or removes it. This will lessen confusion on dac choice upfront and offers system matching flexibility. It's totally cool. Contrary to what some have posted on forums, it's absolutely stable and doesn't harm or hinder your system in any way shape or form. Now there is a the TubeDac+, which has some premium parts in spots, but is the same dac circuit wise.. There is now a beefy 4 amp desktop transformer that ships with all TubeDac.."
what i'm wondering is if the 3Xac sonically superior to what i got with my TubeDac+ ? on the website
www.scott-nixon.com it is only listed as an upgrade for the standard TubeDac.