Is it an amp that uses a hi-freq switching power supply?

I've tried to Google this concept, but it's still quite unclear to me.

TIA

Check out the Tripath data sheets for typical applications, because they will kind of show you what they're doing. It achieves efficiency like a switching supply, only the signal that's switched is the audio signal. The output is a high-current digital pulse train approximation of the input signal. It is sampled at a very high rate so the pulse train is a close approximation. Summing to provide D/A conversion is done in the output circuit.

Wayne