I have been using Esoteric K-01XD with G-02X master clock since past 3-4 days. The improvement is definitely not subtle. It is not going to make jaw dropping change: that is not what it is meant. Simple way of summarizing is that it makes good change in every spectrum: Adds a little sparkle to highs, little sweetness in the mids and the lows are more deep, controlled and tight. There was increase in the soundstage (vertical more than wide). A sense of air around instruments also makes this very special. It makes your DAC get better by at least 15-20%. I have not heard K1X but I was told by dealer that K1X was better than K-01XD + G-02X. Not sure about K-01XD + G-01X (more expensive masterclock) compared to K1X.
Of note, I am using same masterclock with aurender N20 and the improvement is big. I am waiting on new masterclock BNC cables to arrive to use it with etheregen switch and SOTM Snh-10g.