I have heard both the dCS and Berkeley DACs in comparison but not in my system. Maier Shadi at The Audio Salon in Santa Monica carries Berkeley, dCS, Wilson, D’Agostino, Transparent etc and is a most accommodating proprietor. I chose a partial dCS Vivaldi stack ( no transport since I use a NAS directly into the Upsampler) but easily understand the allure of the Berkeley. I also run the DAC directly to my Momentum S-250. I had Transparent XL Gen V balanced ICs custom tuned to interface between the Vivaldi DAC and the Dag and have yet to find a preamp that improves on that setup.
Heresy, I know!