After previous experience with DAC building i choose now to build modular construction, where S/PDIF decoder is separated from DAC. It allows to try many types of DACs without need to change S/PDIF decoder board. Eventually we can build S/PDIF decoder with other circuit for example CS8416 or build USB DAC. Interface between decoder and DAC is standardized I2S bus with additional Master clock signal, which is needed for using DACs with oversampling and +5V for eventual TTL logic. Decoder and DAC modules includes power circuits. It's possible to connect modules to separated windings of power transformer. When we want to connect DAC only with USB and we haven't interested in S/PDIF input that we can use USB DAC with direct I2S output and electrically isolate him from DAC for avoiding potentional ground loops and interference.