[Teenage diplomat]

I’m sitting in my living (listening) room playing LPs and marveling yet again at just how good these speakers are.  Every bit of the break-in harshness on top has disappeared, replaced with an utterly realistic, extended treble.  But the things that gets me every time are how good vocals sound, and the total lack of the bass boom I used to have with my former speaker.   Have I heard better speakers?  Yes - but not in my relatively small rectangular room.  In my room, they wiped the floor with the speakers they replaced, PSB Imagine T3 floorstanders, which were Stereophile A rated.  The M4s combine the best elements of that speaker with the openness I enjoyed when I had a pair of Maggie 1.6QRs.  All I can say is that I’m happy with them, and don’t expect to replace them anytime in the foreseeable future…unless the new S6 is somehow significantly better…;).

[Daryl Zero]

Nice. I've had my X5s for over 3 years and I expected them to be my endgame speaker for my main system and so far that is still true with a lot of the same attributes you ascribe to your speakers. They still amaze me.

[Mr. Big]

My M3's Sapphires continue to bring enjoyment, what I like most is they are like good Electrostatics ESL's but with dynamics and punch. As I've learned about setup and how the speaker reacts to the placement and toe-in, they better have sound. I owned a lot of good speakers in 40 years, and these fit right in that group, they were better not really but they sounded different being a box design, and the best of them being the Dynaudio Confidence 5's that today would be costing 20K or so. I've stopped looking for the holy grail. Still, with the experience I know in synergy and cable matching and room acoustics getting them right pays more upside than constantly changing speakers and gear, which I've done over the years and all I did was chase my tail and start all over again. These are solid speakers and balanced from the bottom to the top, and the top end is not bright at all now but open. If I were to change speakers it would be going back to a pair of Quad ESL 57s, a speaker I've never owned yet, but I have no urge to and I loved the 57s when I heard them so 30 years ago, they were so real-sounding and natural but with the drawback, if you pushed them too hard with the M3's Sapphires I have very little worry about that, and I've found they like current and power and I don't care what the DB ratings are, Quads the same, they just sound better with power even if you don't play them concert level loud.

[AllanS]

I’m also two years and change into my M4 experience.  In those two years I’ve learned that I’m seemingly deaf to many of the subtleties you all hear.  Tweaking speaker position / toe doesn’t make much difference to me as it relates to tonal balance and such.  It doesn’t seem to matter how I set them up, they just sound good.  Maybe that should be their pitch.
That said I do agree they offer a nice balanced sound across the frequency range and there is an effortless that comes with plenty of watts on tap.  The notion that unused power reserve makes a difference makes no sense to me, but they seemed to like the PS Audio M1200’s I had pushing them till late last year.
I may be semi immune to positioning and such but there are a couple of sound quality attributes that I love.  Low-ish volume response is excellent in IME, specially bass.  I’m not a thumping bass head but there is a nice fullness to the sound at lower volume that I enjoy.  Piano is a given.  Percussion is crisp. Voices, plucked instruments, brass and woodwinds are excellent in their harmonics, especially in small ensembles.  I like my sax wet and breathy.  Some of this may relate to the odd choice I have for equipment but it seems to be working.
I sold off the PS Audio setup last year and am starting over again beginning with a NuPrime AMG STA.  I was and still am unsure about what DAC and pre to mate it with so I’ve been driving it with a Schiit Lyr and Bifrost repurposed from the desktop setup that was replaced by a PS Audio Sprout.  I’m always looking and considering, but fortunately it’s good enough that I’m in no hurry to replace them.