I am interested in buying a pair of M3's this week. Anybody know the maximum safe SPL level for the M3?
The question may be about what is safe for the loudspeaker (vs. the listener). I use the M3 Sapphires in a room that is about 18x14, and I sit 8' feet from the speakers. When I spoke to Clayton shortly after the Sapphires arrived, he said his room is about that size as well, and the Sapphires should easily provide more volume than I would want in that setup. That has proven to be the case: with a calibrated sound meter, I'm listening at the low end of the 83-93 dB range, with anything 90 or over being only occasionally (not even once a week for an hour). This is plenty loud for my needs, and I listen to a variety of music from symphonic pieces to intimate acoustic tracks to live rock concerts.
I'm sure Clayton (or others here) could give insight on other scenarios. I think if you have a much larger room and will be sitting 12 feet away from the speakers, for example, and want to get to 90 dB at the listening position then it would definitely push the speakers harder than my case.
Spatial now makes a very good range of sizes in both the X-series and M-series to match up well with the room and listening position and amp.
It's definitely worth giving Clayton a call to confirm the M3s are the best choice for your circumstance.