My bad it turns out. Evidently the cat turned on the crossfeed as denoted in the LED display "C.F." I spent some time through a few settings in Windows and JRMC to get it to do what I wanted. The m9XX forces 96kHz sampling when using DirectSound. In the end, I set up JRMC to use WASAPI and output a proper 44.1kHz to the m9XX. Using these settings, I must say that the m9XX sounded pretty good.
Exceptionally good? No. But decent. Pretty good in fact. And very far from bad. (To put things in perspective, keep in mind how many other portable DAC/amp units, some over two thousand dollars made me go huh?) There were no odd treble characteristics (it's the new AKM chip after all, and I don't think AKM has ever made a nasty sounding DAC chip). A little bit on the warm and relaxed side.
As for the crossfeed implementation, I am not a big fan of it. It sounds like a bloomier version of an ancient Rockbox implementation on my old iRiver "Soviet" iPod player, except even more bloomy and reverby. As an aside, I think HeadRoom probably had the best hardware crossfeed implementation (on their top tier amps) ever. I also like JRMC's software crossfeed (I know the JRMC crossfeed isn't the best solution, it's still an acceptable one.) I am not against crossfeed in general and frequently use the JRMC implementation on headphone systems which could not project depth in the soundstage. I am however against subpar crossfeed implementations, and it should be obvious where I stand in terms of the m9XX's crossfeed solution. In the end, not a big deal. None of the other gear being compared have crossfeed at all.