@izgmoen The LHY ock-2 has a MCLK output of 10 Mhz which is compatible with the Gustard. It has a selectable output impedance of 50 or 75. It outputs sinwave or squarewave. If I'm reading correctly, the R30 will utilize an external clock for the USB input and streamer input. I'm not sure about I2s.
The R26 was a big improvement over the SMSL in overall sound quality. The X-30 was an step up. I think that all three are good at their price points.