I was and am a big fan of the original Mk I. I found it to be very revealing and musical, and it was competitive to several high-end DAC's in our listening sessions. The Mk II is a significant upgrade. To best describe the improvement, I'll borrow the well-used visual metaphor of cleaning a slightly dusty window or "lifting a veil". It seems that the noise level has been pushed down and transient fidelity increased, which leads to an improvement of presence, greater apparent dynamics, more detail and clarity. Yet it is not strident or edgy. Soundstage is more clearly defined with improved 3-D spacial resolution around sound sources. Overall it's a big step toward a more lifelike presentation.
Congratulations to Kevin and Dave for offering a real sonic upgrade to their RAKK dac (and such a an easy and low-cost upgrade it is). CD sound just keeps getting better and better.
Jim