Does this mean that the receiver will deliver more power at lower ohms? Is this done automatically?
Yes and yes.
As the resistance drops in the speaker the amp is able to produce more power this results in more heat produced by the amp and is the reason why many receivers will shutdown with low resistance 4 ohm speakers. Denons appear to be able to handle this lower resistance/ heat build up better than most, not to say others are not able to run 4ohm designs as well. Grunt and many others have Onkyo's driving their systems and have worked very well for them too; albeit with reports of possibly a little more heat coming from the avr requiring a fully open placement to help dissapate the heat.
