MAC Autoformers?

I'm by no means an engineer, but very much appreciate the technical descriptions of why some amplifiers are designed with autoformers.

One comment about McIntosh owning the patent.  The patent on that invention expired long ago.  I think the more viable reason more amplifier manufacturers don't use output transformers for solid state amps is the cost and how much weight it adds to the unit.

I spent about a year visiting all sorts of shops to shop for a new pair of speakers.  The pair I finally selected (Focal Sopra No2's) match up with the MC452 "quad balanced" amplifier from McIntosh.  I've heard those speakers driven by amps which were called "fast" or "more detailed" (higher damping factor?), but the Mac (to me) just sounded more "musical" than the others.  Could it be the autoformer?  Maybe.  But I wouldn't sweat it if it was not!

There is a reason why they retain value, and I really don't believe that it is the blue meters. They sound good, and from my experience, the amps with autoformers have more authority and "gravitas" I guess I'd say.

The only negative with Mac autoformers is in doubling the amplifier cost and weight.

I have been looking at integrated amps and when researching the Mac I noticed the only ones without auotformers are the lowest rated at 100w. I wonder why that would be the case are they not needed in the low watt amps? I assume they could use them just as easy in a 100w integrated as a 200w integrated. I belive they use the autoformer in all the new power amps even the lowest 150w mc152. I don't own one or know  that much about it just curious why only the low watt amps don't have them ? Could it be they are meant to be used in smaller rooms with easier to drive speakers? 

" The only negative with Mac autoformers is in doubling the amplifier cost and weight"

So true!  I had to get help from my neighbor to get the carton from my car into the house, get the beast unboxed, unbolted from the plywood base, and lifted up onto my wall unit!