which nad amp sholuld I get?

I dont want more power, just reserve power for orchestral peaks (exactly)

I am using b&w bookshelf speaker and my room is 11x12'

If 60 watts isn't enough, 70 or even a 100 won't be either. You should at least double the power or get something with a lot of current.

Well, I guess you have to put both your amp and your speakers into the equation. If your present setup is crapping out on orchestral peaks, you have a headroom problem that won't go away with only double the amplifier power. You will need more like six to ten times more.

(This is because of the dynamic range of an orchestral performance. Crescendos and tutti can pack a real wallop. For a peak that doubles volume for more than an instant, your amp needs to put out ten times the watts.)

B&W speakers are not known for their efficiency, and bookshelf designs in general tend to be a tad more power-hungry than larger ones. The solution may be to find a more powerful amp AND get more efficient speakers.

C352 floats my boat in my second system
Larry