which ProAc speaker?

In the room you have 11,5 m X 8 Met is
37 feet X 26 Feet
I would suggest you try at least the 140 MK 2s or D 28s
The D 38s would be even better.
Best Johnnyr

The Studio 140's are good speakers, I almost bought a pair once. I haven't heard the D series.

that is a HUGE room ... not sure ProAc's are even the best choice for a room that size. I hope you are not going to be sitting 20ft from the speakers!

Proacs would sound great in that room. the D38 speaker moves plenty of air to fill your large listening room. They are the most user friendly speakers I have ever come across, very forgiving.

Look for a pair of response 2.5s,

D28, would be a good match with the MC 275. D38 would be even nicer, but the MC 275 may be a bit small to drive them well.

I had the D2 the D-15 and the tablette 2000 signature. Strangely enough I had the most enjoyment overall listening to the tablette model and never quite fell in love with the proac sound other than the tablette. They seemed pretty system dependent and they didnt always have the magic but when they did it was pretty good for such a cheap speaker. They are what drove me to try higher up the line but I never really liked those speakers though I tried. I prefer Dynaudio personally so that might give you a good idea where I'm coming from.

Well, I tried out my Berning preamp with an Audio Research solid state amp at a Dealer recently, using Dynaudio Focus speakers. The sound was clean, but too forrward and veering on brightness for my taste. I then took the amp home for further listening thru my Proac Studio 200s and the system SANG like I could not believe. The Berning and ARC combo was way better than at the Dealer's; with a spacious and intoxicating air to it. I then started experimenting and swapped out for some silver cables, and half the magic dissapeared!
All this to say, everything is really system dependent. Proac and Audio Research in particular, are still a natural match. Also,to me it seems, one should use the smoothest and most refined cables you can afford...

The Studio 140 Mk 2's are great (espeacially) for the money. I would say they are at least 90% of the D28's.

Thanks everybody for the comments! I will try the 140 mk2 and let you know.