Do I need speakers upgrade?

How far away from the speakers do you sit?  How much space is there between the speakers and the wall behind them?  With the D48s, seems like you're going for more quality and more bass.  Other priorities?  My guess is that people will recommend some stand-mounted speakers and, possibly, a (small) sub.

I sit  9' far from the speakers and the space between them is about 6.5'.stand-mounted speakers is not an option for me I don't like them it's more easy for them to "disappear " in space but always find them restrain and laidback compare to floor speakers .

Spend money on room acoustics first. They will make your room more speaker and sub friendly.

GIK Acoustics for advice.

What you need is a loudness curve, eg, dynamic EQ.

Don't get me wrong I am very statisfy with my setup and there is nothing wrong with it however I think I am ready for higher step up
for my system this is why I am considering speakers upgrade one of the 3 options I mentioned .

You absolutely need the bigger Proacs. Don't let anyone tell you differently.

No brainer - the Proac is the best of your short list, by far!

I have the Proac D-40r in a room 11w 17d 10h. They are the model preceding and about the same size as the D 48. I think the D-48 could work in your room, and the D-30r might also be a consideration

Thanks jperry !
Everyone worn me that the Proac 140MK2 needs more space than mine but I ignored them and it turned up to be just fine. Do you think that that the Mcintosh MC 152 is enough for the D48R ?

Uour best speaker option maybe yo keep them.
If you or a friend can solder , replacing the not so great stock crossover parts with 
Much higher quality  crossover parts , are not that expensive 
And can transform uour loudspeakers .  I recently did mine and it was at minimum a 2- 3X the $$ cost upgrade. Everything is far more detailed and refined.
If Anyone has any questions tell me what uou have and I can at least make a few 
Recommendations based on my 20 years in modding equipment.

The Proacs are easy to drive so your mc152 should be able to drive the fine. Hopefully you can try then first.

audioman58, this may sound native, but would it help if the stock components - particularly the caps, are replaced with higher quality but equal spec units, or modding requires in depth knowledge of the circuit and modifying the stock design/specs?

You have not really let anyone know what improvement in sound you are looking to achieve.  Larger Proacs will give you a bigger Proac sound.  If that is what you are looking for, then go that direction.  What about soundstage, what about total dimension, what about the TONE, air around vocals and instruments, instrument placement, definition, decay of notes?  What does piano sound like, what does the sax sound like, what does the violin sound like?  IMO your front end is the weakest link.  How did I determine that, well I build DACs, preamps and phono stages.  These custom made products do certain things that most people have never heard before.  They bring out the systems potential.  I don't know what you expect your system to do, but without all that information, it is hard to make a specific recommendation.  I can change the sound of your system with just a few resistor changes, cap changes, or adding a choke.  It could be that simple.  Happy Listening. 

Hi bigkidz

When you say my front end is the weakest link you mean that my current speakers are the weakest link in my set up ?

My room is larger than yours (see my system page for full details on room and components) and I think I have plenty of speaker for where I listen.  I only listed to the ProAc Studio 125 (beautiful midrange) and ProAc D20 before I ordered my 148s.  Why did I go with the 148s?  They have the same (non-ribbon) tweeter as the current D response line, same great midrange (125 still had better) and have better low end control with the 2.5 way design.  I've heard the 148s are a more refined version of the 140 mkII as they went to different drivers.

I would consider the following upgrades for your 140 mkII ProAcs:

1.  Get some Soundocity SEV9 outriggers.  I use these and are much more rigid and stable than the factory ProAc spikes.  The SEV9s are also flexible enough to use with other tower designs.
2.  Upgrade your speaker drivers and crossovers to the 148's configuration.

Does anyone have recommendation for crossover upgrades for my Studio 148s?  I would love to get my 148s even closer to the 125's midrange with an even more refined sound.

I have heard the Studio 148 and didn’t like it at all found it aggressive , rough and not enough agile compare to mine 140MK2,
Unfortunately I can’t audition the D48R in my country managed only to listen to the D20 which I liked very much but the bottom end was clearly missing ...the D48R seems like the ideal upgrade for me despite its very high cost .

  If you're overall happy with what you have then the D48R seem the obvious choice if your comfortable with the price.  It should really let your McIntosh sing.  Just checked the ProAc site & it looks like they're updating the D30R to a D30RS, using the updated driver tech of of the D48R for a flatter frequency response, but not changing the cost. Could be an option.
  Generally speaking I find the ProAcs to be more lively & exciting than Monitor Audio which is very neutral & refined, but less engaging. Of course this is more noticeable on their mid & entry level products than higher up the range, but still seems to hold true from what I heard at AXPONA. Anyways, I'll be upgrading from the MA Silvers to ProAc Studios next year.

Hi gnostalgic

The D30 is a very good speaker but I do need the extra driver of the D48R to maintain  the 2.5 way I have in my 140MK2 , going to 2 way of the D30 is not what I am looking for.

I do agree with you that the Proac have more engaging and exciting sound than the MA .

I disagree the 148s are rough and aggressive. I think they are very accurate (studio characteristics). Itzhak, the 148s you heard must have not been broken in as they do take a while. Or the source electronics or material was poor. 

Maybe you right the 148 were new just arrived to my dealer and have not been broke in yet ,and now I remember that it took me more than half year for my 140MK2 to opened up to perform at their best.

As advised earlier there is nothing wrong with my current setup I just fill that my amplification can do much more than the Proac 140MK2 , The D48R seems like a big step up for my system .