Warm and accurate bookshelves that can handle volume

I also love Harbeth but would question them for orchestras at volume. I always feel I start to hear the case resonance limits when I listen to orchestras on them but perhaps a better amp would help as suggested.  

I can’t think of any bookshelves that can do a full orchestra well - would have suggested trying b&ws as most likely to work. 
 

how was the paradigm? 

How big is a 'big room' and how lively or dead is it acoustically? Do you have a target peak SPL in mind? Finally, how far is it from you speakers to your listening position? Volume level is a physical parameter that is easily calculated. If your requirements are greater than the speakers capability, the move on. E.g. KEF LS-50s are rated for 104db peak @ 1M and 100W. 2 speakers +3dB, and applying the inverse square law (2X distance = -6dB in level), so sitting 6 ft from a pair of LS-50S your peak SPL would be 101dBA. In a room, depending on size and acoustical treatment, you might pick up a dB or so. Sitting 12ft, lose another 6db in peak level. A larger bookshelf might pick up 6dB in output, and 4-6 dB in sensitivity. YMMV, so do the math  math first to see if you're even in the ballpark.

I go along with henry53. If a system is always warm it's colored . Input varies and the system should mirror that unless you really want it to be warm all the time. It's a valid choice but it's not accurate. You can't have both. You can't even always have smoothness. Some instruments blare like brass and if they don't on a good recording the system is at fault. I remember Gordon Holt was always bothered when a bress recording wasn't in your face a bit.

The Neat Ministra is an isobaric design just reviewed by Mark Phillips at Part Time Audio, and they seem well suited to your needs.  Check his review out.

B&W 805D

Happy Listening!