Focal Scala or Diablos with subs?

If I were you I would try first to integrate your Diablo with your current sub before taking a final decision. Read this post for more info about sub integration:

SubWoofer Help ASAP...

If however, the upgrade bug has bitten you already, then I would proceed with caution. Please do not take this the wrong way, but for somebody into hi-end audio who's father is a sound engineer your knowledge is surprisingly limited. I will try to clarify my statement as it is not intended to be arrogant.

Firstly, there are three main advantages of sub-monitors combos over large speakers: 1) the ability to place the sub in the place that will give you the best bass response, and 2) isolate the monitors from the strong vibrations generated by the subwoofer, and 3) the ability to place the monitor in the room in the position that will yield the most natural midrange and the best stereo image. Placing the Diablos on top of the subwoofers will negate the first two advantages.

Secondly, unless your speakers are symmetrically placed with respects to all room boundaries (often not even then) the response of the two speakers will never be the same. The larger the speaker the more it will interact with the room. Now, because of this, and also because you mention that the position of the speakers and listening chair are basically fixed, it is more likely that a sub monitor combo will work better than large speakers. However, since every room is different one can never be sure of this. (The Scalas have the bass adjustment knobs so they are more flexible than "normal" speakers.)

My advise will be to try to convince the dealer to bring the Scalas to you home. Make a deal with him, e.g. if you do not keep the Scalas you will pay him by the hour. Also, I would not trade in the Diablo but try to sell them myself (but this depends on where you are located). The Diablo are rather rare on the 2nd hand market so chances are you will get a better price for them than your dealer will offer you.

Finally, I want to make a comment about (2nd hand) Focal Scala speakers. For whatever reason I have seen quite a few Scala on the 2nd hand market (here in Europe they go as low as 12k euros). I've even started a thread about this here on audiogon but did not find out much why this is the case. Probably just a coincidence...

Good luck and keep us posted.
Paul

Bo1972, I believe your comment about the REL was address to me. Firstly, IMO the concept of slow subwoofer is a misnomer. Most often it is the resonances in the room that give one the impression that a sub is slow, i.e. bass notes hang into the room too long. This is most often a problem with the set-up and with the room. Secondly, while indeed a old subwoofer, the REL Stentor 3 is certainly not a bad subwoofer (I had great results with it with and without electronic room correction). Surely, there are much better subs these days, but this has nothing to do with the OP's original question. Finally, thanks for reminding me to update my system page.

Neuphonix, I have re-read me initial post. I am sorry for being so bold. I was probably not that happy to realize that in 10-15 year my daughter me also not know that much about drums or speaker set-up or things that I do for living (e.g. physics, math, programing). :)

Bo1972, I agree with what you are saying. Electronic correction has come a very
long way in the last years. I use an Accuphase room correction unit for some
time now with wonderful results. IMO it is a must for SOTA bass and stereo
image.

Initially I though that we are digressing but not anymore. The OP should be
made aware of how seaming-less subs and monitors can be integrated these
days using room correction units.

Tubesrule, Scala seems to be very flexible. Not only it allows one to adjust the level of the bass and treble, but one can also adjust the position of the tweeter and midrange drivers to time align them at the listening position. IMO these are very important features that can make a huge difference if used properly. I do not think Viva has these features. Also, the Scalas go much lower than the Vivas.

Neuphonix, room correction systems can make a huge difference in the bass. However, electronic corrections should be applied only in the last step. Running the room correction procedure without optimizing the system first (i.e. place the speakers and subwoofer(s) in the best positions in the room) will almost always suck all the life out of the music.

I find it a bit hard to make a recommendation in this regard. I use an Accuphase DG-38 with great results. However, they are expensive and not that easy to use as the instruction in the manual are extremely vague (I know quite a few people who dumped them as they where not able to figure things out). Lyngdorf system seems to be more user friendly. However, I heard them doing both good and bad things, i.e. wonderful music when used with decently optimize rooms/systems or sucking the life out of the music when used in bad rooms. Probably your best bet will be to find a dealer that has some experience with room correction system and ask him to demo whatever he/she is using in your home.

Regarding your father comment about the price of the Scalas, I have found it very funny. However, I am not surprised at all. I get the exactly same comment every time a professional drummer sees my drum kit. Unlike we hobbyists, professional (drummers, sound engineers, etc.) can do their job just fine with much less expensive equipments. :)

Finally, it is interesting to see that dealers (all over Europe) have problems getting rid of the Scalas. I do not think it is their performance, just this bad economy. Most likely, getting rig of other large and expensive speakers is just as problematic.

Bo1972, the Lyngdorf room correction system can indeed suck the life and emotion out of a system. However, IMO that happens only when the unit is misused, e.g. one has a lively room and runs the room correction procedure too many times in order to obtain a perfect response.

If I remember correctly the Lyngdorf room correction module lets one know how much correction have been applied. Of course, things will not sound good if 20 - 30 % corrections were applied. One should understand that room correction should be done as little as possible and only in the last stage of the set-up. That is, only after everything else was optimized properly.