Digital Amplifier Company. Tommy O'Brien's class D's are not an off the shelf module purchased from another company. He designed the amps himself, and they do everything right. Airy, soundstage, wide band frequency response. I have two different versions, the original DAC 4800 upgraded to a Mega version and two STM Cherries. I also have a DTM on order. For me, they just present the music better.