Matt,
I'm glad you are digging the Big Six, like Charles said the Lamp DACs are music makers, they present the music in a natural way that many DACs just can't do. I'm sure the Empirical, Berkeley, Auralic, and many other DACs might measure better as far as noise and all that, but can they get you emotionally connected to the music. Musical preferences rule the day, so what gets me immersed in the music might not be another person's cup of tea. But if you already like the sound then you will learn to really love it.
Take it slow and roll in the tubes, hopefully you will hear positive improvement like I did when rolling glass in the Big Six.
Since you are running a Mac Mini like Grannyring, the OffRamp might be the missing link, but in my experience and some of my crazy friends, we preferred using the USB input straight into the server (but mine is PC based) rather than going through the Sonicweld Diverter. So in some cases the BSB might be good enough or even preferred. The convereter gave the sound more focus and slightly better PRaT, but you lost quite a bit of the magic 3D spaciousness of the Lamp DAC. Just my experience, so I thought I should share.
Will be cool to follow your DAC shootout, lots of big names in that mix. Enjoy the DAC my friend, I miss it already!