Owning a Sunfire Cinema Grand 200X5 I would agree that a portion of the amazing sound is the tracking downconverter. The other real beauty is that sunfire amplifiers never seen to product anything more than room temp heat. This clearly has an affect on the sound of the unit. I have experimented with many other amplifiers, Acurus, Aragon, Classe and to me the Sunfire makes then all second class. Not that they are Best Buy electronics, but next to the Sunfire, no competition. The other and not to be overlooked attribute is that all Sunfire amplifiers as my knowledge takes me conform to OHM's law of doubling the power output as the impedance halves, this is the hallmark of a world class amplifier.
I my humble opinion Sunfire amplifiers will run with amps costing 2, 3, 4 or even many times more than their cost.
Thanks to Bob Carver.