The audio signal is transmitted via a USB interface processor to a digital audio bridge. After being processed by an FPGA, it is sent to the R2R DAC for 4-channel output after decoding. Then, it passes through two Ti OPA1642 op-amps for low-pass filtering and single-ended analog signal converting, and transmits to the NJW1195A electronic volume control chip for precise volume adjustment. The output stage uses two SGM8262 op-amps for 4-way phase inversion and amplification, resulting in outputs of singed-ended and balanced analog signals.
The audio circuit features gain controls. It is complemented by a specially-designed headphone protection circuit and a pop noise elimination system, ensuring the audio circuit is both high quality in sound produced and reliable.