After running the Weiss 501 DAC for over a year, Tom at Big Ear in Tempe suggested as good as the Weiss is as a standalone, it could use some help from a quality preamp. So, with unchecked sanity, I plugged in a Luxman C900u and he is/was correct.
Found used, the Luxman cost/performance issue could easily be called into question. But, the improved performance is there. Quantifiable in percentage gain, no. Suffice to say it's shiny and sounds gorgeous. It comes down to defending the cost of the one month stay in Switzerland. Not really cost effective to others, and why should we care as they may have spent 10K on a Super Bowl weekend.