the mini DSP will give you control of equalization and crossover to your mains (rather than using the plate amp crossover). I guess it might double as a dac (i'm not sure) but in this scenario we're using it for EQ which is necessary for any decent subwoofer sound quality to integrate in a room properly. IT's not a knock on the emotiva sub, as it's a well designed sub and perfect for a small room, but a knock on the nature of bass.