The 2200's amp is a hybrid: class AB up to around 80W, then class G beyond that. A class G amp uses a power supply with a series of voltage rails and switches between them so that the power supply output more closely matches the actual demand at the time. From what I've read, this is not the same as the type of "switched power supply" that's being discussed here (those switch the current on and off very rapidly to control the output voltage, so it's a different sort of switching). At least that's what I understand of the matter - hopefully someone better versed on power supplies can sort us out if I'm wrong.