A common rule of thumb is selecting an amplifier is that the power rating should be 50% to 100% greater that the maximum power handling of the speaker if you are concerned about thermal overload (blowing out the speaker). The power rating of an amplifier is based on a connected load, usually 8-ohms. It is also based on a nice, clean sine wave signal. The music signal is not a sine wave but of one with dymanics (as Gregm notes above). This will cause more of a load on an amp to get the music signal as loud as the reference sine wave signal. That the reason for the higher amp power selection.
The low side of the recommended speaker power is to prevent the amp from clipping if you attempt to play at higher volumes. Clipping can damage a speaker driver just as easily as an overload - especially with digital sources which have very high dymanic swings.
So, you will be okay with 200 to 240 watts. But as Kchahoc states above, if you are reasonable with the volume control, going above 240 wpc will not be a problem. The best thing to do is to contact B&W as ask if the make and model amp has any problem they can foresee.
The low side of the recommended speaker power is to prevent the amp from clipping if you attempt to play at higher volumes. Clipping can damage a speaker driver just as easily as an overload - especially with digital sources which have very high dymanic swings.
So, you will be okay with 200 to 240 watts. But as Kchahoc states above, if you are reasonable with the volume control, going above 240 wpc will not be a problem. The best thing to do is to contact B&W as ask if the make and model amp has any problem they can foresee.