The optical (also known as TOSLINK) input on some DACs is capped at 96kHz (even if the DAC itself is capable of handling much higher sample rates). Because the streamer outputs at the original sample rates, and cannot resample to a lower rate, this means that some DACs cannot play 192kHz files through this input. An alternative is to use the analogue outputs on the streamer connected directly to your amplifier. You can keep both the optical and analogue outputs connected at all times, and simply switch to the analogue route when listening to files at a sample rate higher than 96kHz.