My room is 11'5" wide by 15'5" long. Speakers are a little under 7' apart centerline to centerline, and a little under 9' from the listening position. Toe in around 15° but I think I will try less toe. I tried 19 different positions, moving the speakers incrementally before settling on the curent spot. I was worried about using the larger M3's in such a small room, but they work amazingly well. As I mentioned, the open baffle design has advantages in small/difficult rooms. Hard to imagine a box speaker working out as well.
And yes, I am using a 21wpc tube power amp that drives them easily. The 93dB rating of the M3's means lower power tube amps can be utilized.