I think the used DS DAC is the audio steal of the decade. In my system it sounds wonderful. Vocals tonally realistic without any digital glare. With the right recordings the soundstage has depth and width. It also provides details without fatigue. I don’t use a preamp as it has a remote volume control.
This is comparable to other $6000 DACs and can easily be had for under half that. I haven’t heard the previous software revisions or the Edcor transformer upgrade but just having those as options to me only raises its value.