Fan effing tastic, this is new info to me.  I really hope you don't make a new market bubble in the vintage dac market.

FWIW.  I have hinted at this in some of my posts here and there, but my old and much less than cutting edge d/ac-2000 is currently the king of my Stax rig.  I have yet to find a dac that has come close and this includes some big name players like the pwd 1 upgraded to mk2 which is definitely an up there dac.  Where it lacks in ultimate detail or soundstage it makes up for in overall cohesiveness and a non-fatiguing sound.  It's not too shabby at surprising the hell out of me every now and then too. 

At the end of the day it just meshes so much better in that chain than any other dac I've tried, even including some vintage pcm63p-k, pcm1702, and pcm1704 ones.  I hope the Yggy has what it takes to unseat it someday.

Anyone know anything about the Classe Audio DAC-1? I found one on eBay and picked it up to check out. Sort of risky, as it was hard to find much info on it. Figured I'd just turn around and sell it if it's not my thing. I read a few times that some considered the tonality to be a bit on the cool side.

I also found a Stereophile article with some brief comparisons against the SFCD-1: http://www.stereophile.com/content/sonic-frontiers-sfcd-1-cd-player-page-2

Should be fun to try regardless.

Here's a link to modern implementation of the said DAC module. It is in Russian, tho schematics and FFT's should be readable.

http://www.lynxaudio.net/app/download/8396651493/DAC+Lynx+D50.pdf?t=1411833602

Also fun fact - Dan Lavry is behind the development of the DAC20400. His gold series DAC's also use temperature controlled discrete resistor ladders, so the idea isn't dead.

Yarp.