Speakers in 10-15K price range for Classical music

ATC SCM 50 Actives will do the trick - there is a used pair for sale in your price range (Gordon Holt's Estate - he also liked classical and Panels). ATC are close to Quad panel midrange clarity yet will still do justice to Mahler or rock.

I second the Vandersteen Wood Quattros. Moving up in price to the top of your price range (actually just a bit above) would be the Devore Fidelity Silverbacks and the Verity Leonores. The latter are quite new and I have not heard them yet, but have a feeling, based on my Verity Fidelio Encores, that the Leonores would very much be worth an audition.

Since you did not rule out used, I would also suggest the Aerial 20T's if your integrated has enough power for them.

Good luck!

If you don't mind used, you could look at the previous Focal Utopia Be's. I bet you could find a used pair of Alto's for that price. Maybe even Novas at the top of the range. The inverted Beryllium tweeter produces a very wide soundstage. Paired with the Krells I suspect they would sound great.

Try Sonus Faber:
A pre-owned pair of Amati's should fit the bill in the middle of your price range.
A pair of Elipsa's will provide more bass @ the top end of your price range.

Other speakers in your price range, (used of course), that I would recommend would be:

The Avalon Eidolons, which are very transparent, and image and soundstage very well. (However, they are just slighty less than full range.) My friend used these for years, and he is mostly into classical music. They are fairly neutral and have a very nice tonal balance. They are very pleasing to the eye as well. Used, they run around $10K. You might even be able to find the Eidolon Diamonds for around $15K.

The EgglestonWorks Andra II speakers, (which I own by the way), are somewhat similar sounding to the Eidolons, in as that they too image and soundstage wonderfully. But they are a full range speaker. (Note: they might even have bit of a mid-bass hump - I can't tell if it was the speaker or my room, to be honest, but I think it worth mentioning. I have done a few minor room treatments, and the mid-bass hump seems to have disappeared almost entirely.) They look pretty good too, but IMHO, not quite as nice as the Eidolons. Used they run around $10K too.

Now, your amp will work for both of these speakers, but to be honest, they both deserve better, as both are very transparent, and will sound as good as the electronics in your system are. (I highly recommend Lamm amps, as that is what both my friend and myself used with both of these speakers.)

My two cents worth anyway.
Good Luck in your search!