Ok, I'm back ... again this is not a review
I did a very quick listen to the M2, M3, and M5 tonight. Just playing a single channel and moving the banana plugs between speakers. I only spent about 10-20 minutes doing this, playing the first few minutes of just one song: The Psychic by the Crash Test Dummies. (Picked to zoom in on the low through high mids)
Overall the M2 and M5 where surprisingly close with the M5, as you would expect, having more low end. I’d have to do a lot more listening and need a faster way to switch between speakers to come up with a better comparison. I can tell you both presented instruments and vocals clearly and as far as one can tell by ear seem to span their respective frequency ranges well with perhaps the M2 having the edge here. The M3 on the other hand sounded really muddled in comparison in both mids and low-mids. This I think made the high-mids sound recessed. It’s all relative. The end result was a loss of detail in both the vocals and instruments. I was shocked by how much (i.e. it wasn't subtle) ... not what I remembered ...
A few years ago, I compared the M3 and M22 (a speaker which I think is similar to an M2 sound wise) and didn't come away with this impression. If I remember correctly the M22 just sounded more accurate than the M3 in the mid-highs and the M3 had more low end. Perhaps it was the material I was comparing them with.
The 2nd part of the comparison was just to play pink noise through them … both the M2 and M5 were close and presented what I expected pink noise to sound like. The M3 sounded filtered as the high end of the pink spectrum sounded reduced ... call it dark or muffled pink.
In any case, given this non-scientific short listen I have to conclude that Mojo is absolutely right on the M3 ... a lot of detail is lost in the mid territory.
Hopefully others will chime in with their thoughts and comparisons.
BTW, I still feel the M3 is a pleasant sounding standalone speaker and it's probably why a lot of music that sounds good on it doesn't come off as well on more revealing speakers. That said, it's worth repeating ... you're missing a lot with the M3 when compared to an M5, M2, or M22.
Here's my excellent, no expense spared, setup.
Note the stand that Axiom ships free with every M5!