Luxman m900u monos vs m10u

When you bridge an amp you increase the minimum speaker impedance compared to the stereo configuration. 

I think much here depends on your speakers, and what you want to achieve.  If you have hard to drive speakers, you want true monos or stick with the stereo configuration.

If you have nice to drive speakers (no less than 3.5 Ohms and not reactive) with great channel separation then the m900 is your answer.

My speakers are the Revel Ultima2 Studios. I believe their nominal impedance is 6 ohms. Minimum impedance is 3.7 ohms. Their sensitivity is rated at 87.7. Thanks

OK, the Salons are pretty good speakers and IMO (subjective*) both Luxmans are very good; for perceived speed and power I would favour the m10 -- but you are aware it's a behemoth?

It / both will blow your Salons to the next block; you may not need that much power, unless you listen to Mahler in high volume 😁.

In any case the m10 is worth it as an end-game choice; if not, go for something cheaper (and, arguably, less resolving and with less drive...)

*there's a stereophile review comparing the 10 to the parasound , if I remember correctly, concluding they are close. In my limited experience -- there is no comparison, the big Lux is in another league,  (however great the Para's may be!)

On YouTube, there is a channel named: Jay's Audio Lab.  He did extensive testing with the 900 series amps and the preamp; I think he also had the new 10 series in his listening room, but my memory is fuzzy on this.  Google it or go to YouTube and search his channel. He does a wonderful job getting the equipment, hooking up some of the very best cords and cables to it, and then playing them along with comparing it to other brands.