Bookshelf speakers and complex/orchestra

I am starting to get into classical music (LP) however it seems that my speakers have a little trouble handling complex/orchestra music. The seperation of instruments for example is not as clear as with a slow moving jazz recording. Is this to be expected?

My speakers are sonus faber concertos (bookshelf)
My experience with the quest for 'separation' has been good.
I tend to believe the real control of this is in the amplification. If from an LP, then it is also part of the phono preamp. But the amp is the key to clarity.
I have B&W 805s on B&W stands. A Forte 4a amp (owned from new)
For clarity on large orchestral stuff with aplomb try to look for a bigger speaker - something that has large dynamic range and with a critically damped response (a lean tight bass)

The seperation of instruments for example is not as clear as with a slow moving jazz recording. Is this to be expected?

As you add complexity and dynamics it is much more challenging for a small speaker. I would suggest a three way with a mid range of 3 to 5 inches - this will bring back the effortless sound. In some cases, a double midrange driver in Appolito design will help as most midranges struggle at higher levels. Another option is a horn midrange.
Autodexr, orchestral music is some of the most challenging music for any system to reproduce. Systems that sound fine on small ensemble jazz or "singer/songwriter" music can simply fail to resolve orchestral music. There will be many factors affecting this: source, amplifier, cables, as well as speakers. Speaker placement will also be a significant factor.

I'm not familiar with the resolving abilities of your speakers, but don't be too quick to assume the speaker is your limiting factor. I listen to a lot of orchestral music, and for many years I lived very happily with a pair of 2-way Celestion SL700 speakers. Their ability to resolve the inner detail in orchestral music was exceptional. What they lacked was the ability to play very loudly, handle large dynamics or deliver deep bass. But in my 13x17 foot listening room, they were very satisfactory aside from these limitations.

A simple starting point you might consider is to pull your speakers well out from the walls and listen again. Room boundaries can play serious havoc with resolution and instrument separation.

Best of luck!
Autodexr - As everyone above describes, you're in the land of "the hardest thing to do right" when you're talking about reproduction of complex orchestral passages. Everything contributes (or takes away) from that aspect of recording reproduction.

Small-ish speakers can do very well with complex passages--it just depends on the speaker. I use Harbeth Monitor 30's, which, being monitor speakers, are designed to handle as much as you can throw at them...but it depends on what you throw it with. I was getting really annoyed at Stravinsky's own recording of the Firebird on CD--the loud parts were edgy and grungy sounding. I got an Lp version, and found significant improvement. Sadly, I think the CD medium is (often) part of the problem, b/c I'm using some pretty good players (Wadia, Linn, EAR). I agree with Elizabeth that the amp is a significant factor, too. That having been said, one odd thing that can happen is that on lesser equipment, the loud parts sound okay--you just know something is missing. For example, I was listening at a buddy's house to Bartok's Miraculous Mandarin with a $100 Sony CD changer, through Vandersteen 3A sigs, which I would have thought would have been awful, but it sounded pretty darn good...though I knew we were missing a lot of detail.

So, the short answer is, what you're hearing is normal. The really hard part is, how to "fix" it. I think Rushton's suggestion that you pull the speakers out from the wall (if they aren't already) may be a good start.
I'd have to believe your Sonus Faber Concertinos can do a very nice job with orchestral music if set up properly.

First , of course, make sure both speakers are hooked up properly and in phase (+ to +, - to -).

Then definitely work on speaker placement first if currently on bookshelves.

Early reflections will jumble busy musical passages such as those often found in large scale orchestral arrangements on even the best systems, so if applicable, try placing the speakers at least a couple of feet out from the walls to give everything some roomk to breath.

Moving speakers further apart might also help by providing a wider sound stage within which the large number of individual instruments comprising orchestral music can be distinguished better.

Bass/low end extension with smaller speakers away from walls could suffer as a side effect of optimal placement otherwise. If so, adding a good, well matched sub is a straightforward way to address the problem.

If none of this helps, then it might be time to look at amplification used and other electronics.

Also, are you using decent interconnects?
While I agree with everyone, I would like to second, or third, the value of speaker placement. Get those speakers out (on stands, of course) from the rear wall three times their depth, minimum, and spread em apart as far as you can without exceeding the distance to your listening position while keeping them two times their width out from your side walls. And, put your listening chair at the apex of an imaginary triangle with your speakers (imaginary, hell, measure it, measure everything). A little longer may be preferred at the end of the day, but shouldn't be by much.

And after you've had this much fun, trying toeing your speakers out 10 degrees or so from head on to your listening position. Last, but not least, clear the wall behind your speakers and side walls of any bulky furnishings. I imagine that they're might be some dissagreement on this, but do try it for yourself.
Yes, full orchestral is the real test for a speaker (solo piano too). Most box speakers get bogged down under the pressure. Dipoles handle it better than most, such as, panel, electrostatic, or the rare open baffle dynamic speakers, by eliminating cabinet resonances. As Shadorne mentioned, dynamic range and transients are critical too. Larger speakers usually handle this better, but that also depends on the quality of the drivers and other factors such as the Qts. Very few speakers do it well.

Another factor is how the speaker interfaces with the room. Poor off-axis response causes a dull reverberant field. The very nonlinear reflected sound throws the whole 'picture' off.