I also suspected that something was wrong with MX-U8 firmware, but had to stop doubting it after having seen that the DSD channel mix also happened with U12.
As far as I know, none of the MX-U8 users in this forum has tried connecting it with a DAC with I2S/DSD input (RJ45) and playing DSD files.
And yes, it is the best and the only way to check with another DAC with I2S/DSD (RJ45) input, which is however almost impossible unless I buy a new one.
It seems I'm still awakening, even if it's almost 1:30 PM overhere,,,,,, again I didn't read punctual,,, you have the exact same problem with your U12, hmm, thats very strange.
You were talking about: The designer told you the dac doesn't accept MCLK input, that's something Kingwa is also talking about on the I2S modules page I posted above.
He says:
Performance improve advice:
A,If you had some skill on DIY and had the ES9018 built in DAC.
You can try the below advice.
Both RJ45 and HDMI I2S transmit models, the most ES9018 had not request the MCLK signal,
you can cut the MCLK wire in the source , connect to GND or chassis if it is connect to GND.
Please Note:
1,After this modify, the I2S source only can working with ES9018 built in DACs and the design don't request on the MCLK.
2,The DIY always had the risk , we can't warranty any people can finished the modify succeed and safe on the unit.
B, For compatibility with other brands,the default data line up is : DATA, BCLK, WCK, MCLK, GND.
You can try the new line up but it is may not compatibility with other brands :
DATA, WCK, BCLK, MCLK, GND .
You just want to exchange the WCK and BCLK wires in the input module output side and the output module input side.
Maybe you can try the above? Or, did you simply not connected MCLK?
Regards,
Alex