PS Audio BHK 300 mono VS Modwright KWA 150SE mono VS D'agostino Classic stereo

With a source of the Totaldac d1Twelve’s quality, that’s an excellent start for the signal pathway. I can vouch for the VAC Signature preamplifier. A good friend owned it for 4 years and I heard it over hundreds of hours during that period. It is a true top tier component.  iit  "makes music " if you know what I mean.
Charles

Yes Charles VAC makes some of the finest tube linestage out there.
The only brand that i can think of that could surpass the VACs is Robert Koda but out of reach for most of us.

French reviewer Joel Chevassus  I believe introduced the Totaldac to the public with his 6 Moons review a few years ago. He did an Audiophile-magazine. com review comparison of the Swiss Nagra Jazz and Canadian Coincident Statement Line Stages.  He was "highly" impressed with both.  It'd be interesting to know his thoughts of these two vs the VAC Signature preamplifier. 
Charles 

Well i will have the Nagra Jazz for the home audition of the Ypsilon Aelius ll.

You are certainly taking the path of superb quality. 
Charles