@lordmelton The 10Mhz master clock can not be used to directly run the DAC because it is not divisible by 44.1khz or 48khz. Its frequency needs to be internally converted to 45.1584Mhz and 49.152Mhz word clocks that a DAC needs to process the audio data stream through the PLL (Phase-Locked Loop) system. I think Denafrips / DCS use native clocks directly to avoid PLL-based conversion or internal reclocking.
Goldensound actually demonstrates the jitter (short-term timing) performance is actually worse when 10Mhz clock is brought in as a reference, as you have also touched on.
However, the intention discussed here is to use a more stable long-term 10 MHz master clock to synchronize multiple components—such as the DDC (or switch/streamer) and DAC—as a shared reference, rather than clocking just the DDC or DAC alone. The listening impressions shared by @sls883 support this approach. I’ve also explained the rationale in the post mentioned above.