The amp is irrelevant it's in pure class B. Let's focus on the power supply. Instead of making a whole bridge rectifier let's just add an internal resistance of 200mOhm per supply and a smoothing capacitor. You'll notice that the power supply is not stressed with high peak current but the draw is somewhat averaged, constant if you will. Thus the power supply (transformer, diode bridge) is not strressed. Of course it must be designes reasonably. Like the diodes should be rated at 20-30% higher than the maximum, the tranaformer too etc.
