The HPA-DAC2 accessory card is designed to work in conjunction with HPA Series 2-channel amplifiers. The HPA-DAC2 is a 2-input Dante™ receiver that features digital audio transportation over standard IP networks. The HPA Series 2-channel amplifiers come standard with two balanced line inputs and an accessory card slot to add an additional 2-inputs, giving the amplifier a total of 4-inputs.