Is there any advantage to using either the HDMI or RCA over the other for sound quality. I assume the HDMI is required for DSD files to an external DAC.
Is there any advantage to using either the HDMI or RCA over the other for sound quality. I assume the HDMI is required for DSD files to an external DAC.
Before the invention of DSD over PCM (DoP), HDMI was the only authorized form of digital passing of DSD signal. However, DSD-capable HDMI-receiving devices tend to be multichannel A/V receivers rather than 2-channel equipment. Lumin S1 / A1 / T1 / D1 supports HDMI output of DSD signal. Lumin does not support the non-standard I2S over HDMI, so it's not discussed here.
After the invention of DoP, some DAC will receive DoP from USB audio. A fewer number of DAC will receive DoP from SPDIF. To use Lumin S1 / A1 / T1 / D1 together with a DAC that supports DoP over RCA SPDIF, simply use a BNC (from Lumin BNC output) to RCA converter. Lumin U1 has a RCA SPDIF output, so no converter is necessary. bthomas9 is correct that Lumin needs to be set to DoP in this configuration.
Whether Lumin analog output is better or worse than the SPDIF output to another DAC depends on one's audio preferences, and the comparison of the Lumin built-in DAC implementation against the external DAC.