With this circuit it is possible to provide a TOS-link (optical) input for the headphone amps HPA V100, HPA V181, HPA V200 and HPA V220 and HPA V281.
The optical TOS-link input can be used to connect a a dedicated device via light pipe. 2-channel audio files can be sent to the headphone amp whereas digital audio formats up to 24 bit with 44.1 ... 192 kHz sample rate are supported.
The digital receiver forwards the data to a separate D/A converter offering 110 dB dynamic range and –100 dB THD+N.
The optical input has priority over all other inputs and will mute these when valid data is received.