op
the michi x3 will drive most anything... so the real question is what speakers will work well in that small, almost square room of yours ... and has a sound you will like...
i think your notion of sonus fabers would be great, also smaller harbeths, spendor classics - i think you would be wise to stick with standmounts + sub(s)... will help manage potential midbass bloat due to the room confines that most floorstanders may introduce
i am guessing you are finding those kef r3’s are kinda tizzy...?