Personally I don't like the sound of the B-52's.
The Crown amp you have is a little dated, but has a good power reserve rated at 310 watts per channel @ 8 ohms, 385 watts per channel into 4 ohms (both continuous ratings)
http://www.crownaudio.com/pdf/amps/101229.pdf
JBL SR series speakers would be ideal match for most any Crown amp, but these are actually a little out of most people price range. Take a look at the new JBL JRX series. These are a low budget alternative that retains the sound quality of the SR series but they sacrificed power handling in order to do so. Your amp will power these with no problems.
http://www.jblpro.com/JRX/index.htm
They are very well constructed, have a trapazoidal design for multiple speaker arrays, they can be bought for permanant installs with built in fly-points, they aren't light @ 61 pounds for the 15" 2 way, but by no means the heaviest for the sound quality. Lighter speakers tend to sound boxy & lack bass response - as a rule, there are occasional exceptions.
This will be cheaper than buying the active speakers & sound as good.