unman M-900u for Focal Sopras 2 and 3

That could be an interesting amp to try.  I bought a Pass Labs XA 30.8 for use with some high sensitivity speakers, and also I tried it out with the TAD's.  It was a bit warmer and "gauzier" in the upper bass, low mids than I would like, and it seemed to lack dynamic spark.  Now, it could just be underpowered for the TAD's, clearly, but it was not a good match.  So far, the BHK mono's have been the best with them.
As with all things in audio, you do hear some alluring aspects from the M900u that make you want that, but mixed with the best virtues of the other amps you try - - keeps us wishing, doesn't it!

..yes; Almost like an amp for every mood and album--I once had a dream where speakers were mounted on a 2-D gantry so that the speakers could be optimized per track...sigh.

So I know what you mean about texture in the upper-mids; I still have an XA-30.5 which is an amazing renderer of midrange --deep, dimensional, passionate; Just mesmerizing. In the right system pure magic. On 4 ohm dynaudios the bass/upper can be wooly at times but still very good; 

The INT-250 has some of that midrange dimensional character, not as buttery smooth, but has significantly cleaner and more refined top end; The mids are neutral and have a touch of warmth, not as golden imbued as the Lux m-900 combo but beautiful in own way; The bass power could blow apart most speakers and is never a bottleneck; The INT-250 just digs and digs the more you crank it; Never whimpers or compresses just gets bigger and bigger. I've said this before but this time I mean it ;) a keeper;

I found that Transparent Super Speaker Generation 5 are a great synergy with the INT-250 and speakers; I used to be in the "cables don't matter" camp but I have come a long way since then. 

I do think that the Luxman M900u has very promising sound qualities - - so much so that it gets me thinking about finding the right speakers to match it!  The TAD's are definitely not the right ones, probably more something along the lines of Sonus Fabers would be an outstanding match, I'm guessing.
To stay with the TAD's it would be interesting to try a powerful Pass Labs approach.

Surprising that you did not like the m900 with TAD. The reason I am buying the m900u is because of an audition I had with the m900u+c900u+Luxman DAC ($8K one) + TAD ME1. The best sound I have ever heard from my regular test tracks. I am just getting the m900u and will make the speakers fit the amp, that is how much I liked the amp.

I was surprised that they didn't like each other, too.  I don't know the ME1.  The CR-1's do need some work so they don't present too "light", IME, and this seems to be the issue with the Luxman pre + amp driving them.  The pre with my BHK mono's has a lot to offer (the pre clearly bests the BHK Sig preamp I had been using).  This weekend I get to start messing with an ARC Ref 40 preamp, and maybe this will synergize with the M900u - - that's my hope!  I really have heard a lot to like in both the C900u and the M900u, but with my CR-1's it seems to be "too much of a good thing".