Hello RemyRAD,
Not so long ago Stage Accompany discontinued their smaller and more affordable studio monitor the M44 (formely known as PS44, for home use) which was also a very good sounding monitor.
The main benefit of this enclosure was the use of the smaller Ribbon Compact Driver, the SA8520, with even greater transparency and detail in the high frequenties then the SA8535 used in the M57.
Technical information M44: stageaccompany.com/support/downloadnew/m44_techdoc.pdf
The SA8520 is the pro-version of the Philips RSQ8P (Philips used them in loudspeakers for home use).
The only drawback is the handling power of the SA8520 of 30 Watts (500 Watts peak), but that's no problem for use in the M44.
For long time PA (ab)use the SA8520 was not suited, that's one of the main reasons why Stage Accompany developed "bigger brothers"; SA8525, SA8526 and finaly the SA8535 (and his successors).
Like they say; there's is no free lunch!
SA8520, SA8525, SA8526 and SA8535 (first version with neodymium magnets)
The M57 sounds indeed very detailed, even at very very high sound levels.
Besides the high quality components SA uses also DDC (first used in the SA Blue Box (in the build-in PMS-5000 amp) and the PPA1200 amp) to take full control over the conus movement (woofers) and the diaphragm movement (Ribbon Compact Drivers).
DDC: Dynamic Damping Control actively compensates the effect of speaker cables and connectors between the amplifier and loudspeaker via two send/return wires to/from the loudspeaker cabinet. This system is incorporated in all SA amplifiers and works with all DDC pre-wired SA cabinets.
The sound of the M57's is really addicting, but can be also very frustrating.
Songs that you loved before to hear thru your home HiFi loudspeaker system (because you liked the sound, song and lyrics) can be very disappointed hearing them thru the M57's (taking the joy away because your favourit songs sounding like crap (reason: simply because they're badly recorded/mastered ;-)).
At this level of monitoring bad recordings (and/or heavily compressed) sound really really bad, and perfect recordings (with dynamics) sound really awesome and breathtaking.
It's a pitty a lot of youngsters like the sound of a heavily compressed song which leaves no room for dynamics.
The only thing they care about is how hard the song will blast out of their mobile devices!
One of the reasons some people dislike a ribbon driver is that they're missing something in the sound the ribbon produces.
And that's correct, they're missing the harshness and distortion of the compression driver ;-)
The other reason why people don't like the ribbon sound is that they think the output of the ribbon driver is far less then that of a compression driver.
A system with lots of distortion in the mids and highs gives you the idea that that system is producing far more dB's (and in that believ sounding better)!
A ribbon equiped system stays free of distortion even at very loud levels and gives the listener the idea that the set isn't playing loud (until you grap your dB-meter and start measuring).
That's why you can listening for hours and hours to a SA ribbon loaded cabinet (without the distortion) without going to feel tired after awhile (what is the main reason of my ribbon-addiction).
Because of the above mentioned reasons a SA ribbon loaded cabinet sounds
"how music should sound", without distortion and with dynamics.
Stage Accompany is still looking for a reseller (SA Partner) in the US, so maybe you get ever the chance to listen to a set of these beauties 
Found a photograph of a set SA M59 (one of the first versions, can only be active driven) in combination with three SA PPA1200's (I'm not the one on the photograph ;-).
Bit over-kill ;-), and wrong placed M59's (bass ports must be facing outwards).
Below pictures of the SA Blue Box SA4525 (with the intergrated SA
PMS-5000 amplifier, horn-loaded SA8525 Ribbon Compact Driver and SA1503/1513 woofers) which was the lead to my Stage Accompany addiction.
The Blue Box is a rather famous enclosure devoloped in the '80 and still going strong (and sounding really awesome at my living room) after all those years.
The black "Blue Box" VN310025 (with Philips logo and name are OEM build by Stage Accompany) is a real collectors item (from which I own a set
.
Technical information SA Blue Box: stageaccompany.com/products/vintage/SA4525bb.pdf
The Blue Box was used for 23 years in the Blue Note Jazz Club in New York!
These enclosures sound(ed) so good that some studios use(d) them as mid and far field monitors.
A couple of thousend are been build and sold all over the world in the '80 and '90 (priced at arround 5000 US dollar each).
If you stumble on a set SA Blue Box with the orginal drivers (and in good shape) don't let the chance go by to listen to them, you be suprised (and maybe you get addicted too as I'm)!
In the Netherlands, Germany and Italy the SA Blue Box is still a very popular enclosure (going second hand price now arround 300 - 400 US dollar each).
Three different versions of the Blue Box.
Backside of the Blue Box (with the SA
PMS-5000 amp) that I own (without flightcase).
The back of one of my Blue Boxes (build-in flightcase).
The front of one of my Blue Boxes (build-in flightcase).
Blue Boxes at the Blue Note Jazz Club.
Greetz Webbie...
