A much more stout power supply that will double it's output as the impedance decreases, ie. into four ohms it will be two hundred per channel while the Hafler would be doing good at 150wpc at four ohms. Also much larger power reserves. The build quality and parts quality is also much higher.
Newby question on watts...
I have aquired an older amp, Audio Research D-100 rated at 100 watts. Weighs 48 lbs. Sold my 1st amp, a Hafler 220DH rated at 115 watts, but only weighed 24lbs. What am I getting for the extra 24lbs? Nothing/something? If both have the same output, what is the gain for all that extra weight.