Hi judasmac
I think it's your room. The M3s' driver is mechanically 'integrated' with its tweeter since there is no cross over between the amp and the driver. The simple x-over is between the tweeter and the amp. I replaced the capacitor and resistor in most of my Axiom made speakers and have noticed an audible improvement. Of course, if you do this your warranty will almost certainly be voided.
I've tried Jensen paper/oil, Audiocap Thetas, and some Solen caps and Mills and Caddock resistors with good results. I think these modifications have taken my speakers up a level.
I found my M3s liked to be placed about 2' from the wall and required some decent speaker stands. (I like the stands from Loveland)
One thing that surprised me about my M3s was the bass output. It helped me find weaknesses in the built in cabinetry behind the speakers - lows caused some things near the speaker to resonate. Move 'em out and let those ports work!
Your Tangents sound interesting. I have some old speakers around which also sound great. My garage system is vintage and uses a pair of Dahlquist DQM 905s which sound ridiculously good. (Kenwood KA9000 slightly modified with a heavy power cord and modern 5 way speaker posts, a Kenwood SW300 sub with a Titanic 10" driver and a 15 year old JVC CDP).
I don't want to diss Cambridge equipment, but I had a D500SE CDP which I got rid of because it sounded terrible wth my M3s. I know there are folks who insist that all CD players sound the same, and I'm not sure whether the one I had was defective, but it was a terrible match for my system.
