"When you run the clock cable to the DDC on Ext Ref and then I2S from DDC to DAC, the 10Mhz clock signal is supplied to the DAC via the I2S signal. There is no need to run another clock feed as external reference for the DAC. In this case, the DAC clock should be set to Internal. When used in this fashion with I2S It is redundant to run separate 10 Mhz clocks to both the DDC and the DAC. Saves the cost of an additional clock cable."
I'm not super knowledgeable about some of these connections and need a little help - I'm using a Gustard x26 Pro. I began by using the USB input. My first upgrade was to use a cheap Douk Audio DDC with a decent LPS so I could use the I2S input in the DAC. This was an improvement for me. My next upgrade was an Afterdark external clock. This was another improvement. Now I'm reading the above post and I'm looking at a Gustard U18 DDC. Looking at the back panel of the U18 there is a BNC connector marked as an input "1OMCLK". There is also a BNC output marked "WCK". If I understand the post, I can use my Afterdark clock with the DDC and then simply use an HDMI connection to the DAC and I will get the benefit of using the external clock with the DAC as well. Is this correct? Thanks for any help.