Why nobody uses McIntosh with Vandersteen?

"Mac owners use B&W, JBL, Tannoy, Sonus Faber etc"

McIntosh MC501 monoblocks with Wilson Sophia II's here (4 ohm), no thin problems.

Isn't the "feature" of the Autoformer is to make the amp is compatible with more speakers?

Yes, but Macs don't have 6 Ohm output.

all McinTosh with Thiels

My brother has a Mac and Vandy system. Sounds pretty good to me.

It may have to do with the brand mix that retailers tend to cary. The Vandy dealer near me also sells Audio Reseach. That is their choice for a ultimate high end system, so allot of people end up getting this match. A good match it is, imo. I don't own Vandys (but would if i could own them all) , but would not want anything other than Audio Research.

Funny u mention Mac and S-Faber (Sumiko)- those have become Magnolia Hi-Fi brands that are mainly sold to yo-yos who took out giant home mortgages and went shopping for the most expensive thing at the local mall down the street. Not really the best sounding, but non the less, two brands that get hooked up allot.