@a1uc Nice post, very interesting. I recently heard the Luxman m900u and the c900u with TAD ME1 speakers. I just loved it, so much so that the m900u will be the amp I get. I am hesitant to spend on the Luxman c900u preamp because this system is for my office and it seems like a little overkill cost wise for my small room.
Have you ever tried any other preamps with the m900u?
Have you tried the PS Audio DS directly into the Luxman m900u?
I have realized that I prefer a preamp in the chain but it would interesting to hear from someone with your particular gear.