Using 200w amp with 300w rms speaker

Sensitivity is correct because we are measuring how sensitive the speaker output volume is to the input signal.

My bad.  Thank you millercarbon for explanation.

Sensitivity is correct because we are measuring how sensitive the speaker output volume is to the input signal. This is not the same as efficiency, which relates to how efficient the speaker is at doing work vs heat. The same driver has the same efficiency no matter where it is. In one speaker its used as a horn driver, in another its ported, while in a third its sealed. Same driver, same efficiency, different sensitivity in each case.

Hey just because there rated at 300w dosent mean you cant drive them with 450w! My Dynaudio speakers are rated at 200w and I drive them with a 350w per channel amp no problem they sound fantastic and I love the extra power (so do the speakers). Sure your 200w will drive the more power hungry speakers but if you listen fairly loudly then you will be seeing your amps power guard lights glow a lot! Not the best situation.

Matt M

+1 knotscott

Sensitivity: 90dB/W/m

It means that 1W from 1m will produce 90dB.  The fact that you have two speakers adds 3dB.  Because it is not open space, reflections in the room will likely add another 3dB.  So, your speakers driven by 1W power will produce 96dB from the distance of 1m, 90dB from 2m and 84dB from distance of 4m.   Assuming 4m distance it will be 84dB from 1W, 94dB (twice as loud) from 10W, 104dB from 100W and 107dB from 200W.  It should be plenty loud for you (and your neighbors).

(Sensitivity: 90dB/W/m - it should be called Efficiency.  Sensitivity is rated at 2.83V at 1m.   at 8ohm Efficiency = Sensitivity)

Buy what you like the sound of.  You have excellent amps capable of driving a speaker well. At the level of equipment you have, unless you're doing some really silly things with the system, I wouldn’t even give those specs a thought.  

The power recommendation is for MAXIMUM safe power.

Yes, but it is maximum average power, not maximum peak power.  
Average power is equivalent to dissipated heat.
Pavg = Vrms*Irms    Peak power for sinewave is twice larger than average power.  RMS of power would be about 20% higher than average for sinewave, but it doesn't represent anything useful.  It is incorrect term.   Just stating power in watts means it is average.

300W will be about 12% louder than 200W

Doubling the watts on an amp will give a mere 3db more power. Going from a 200 watt amp to a 300 watt amp will give less than 2db more power. I don’t think that you should worry about it!

The power recommendation is for MAXIMUM safe power.

To gauge the power needed, look at the sensitivity rating instead.

Copied from Enjoy the Music review.

Specifications
Type: Three-way vented-box system
Drivers: 1" decoupled double-dome aluminum high-frequency
            6" woven Kevlar cone FST midrange
            Three 6.5" paper/Kevlar ® cone bass
Frequency Response: 45Hz to 28k Hz (+/-3dB)
Within 2dB of reference response
Horizontal: Over 60°
Dispersion: Vertical over 10°
Sensitivity: 90dB/W/m
Harmonic Distortion <0.5% 110Hz-20kHz
Nominal impedance: 8 Ohm (minimum 3.2 Ohm)
Crossover Frequencies: 350Hz and 4kHz
Recommended Amplifier Power: 30 to 300 Watts into 8 Ohm
Dimensions: 42.8" x 14.4" x 14.3" (HxWxD)
Weight: 73.7 lbs.
Finishes: Rosenut, gloss black, and satin white
Grille Color: Black or Grey (with satin white finish only)
Price: $3999.99 per pair

30 to 300 wpc amplifier recommendation gives you a wide range of amps to work with.  Your Mac at 200 wpc should be absolutely fine with the CM-10 S2.  If one was pushing an amp to run at 200 wpc continuously then one is headed towards hearing loss or already suffers from it and might be better served by high efficiency Horn speakers or much larger floor standing speakers that can absorb that steady power input without blowing voice coils apart, especially on transients.  Not to mention there’s little headroom left from the amp at peak rms so clipping will be destructive.  At sane listening levels and average sized rooms the Mac / B&W combo should be more than satisfactory. 

The recommended power for the CM10 is 50-300 watts with 8 ohm impedance. Sensitivity is 90dB, although independent measurements reveal a sensitivity of 88.5dB. Your amp is very capable of driving these speakers.
I couldn’t find the impedance curve across all frequencies, but the reviewers state that these speakers are easy to drive. Even if impedance dipped down to 4 ohms your Mac would still be able to handle the load.
You should ask the dealer to confirm.

The power requirement of a speaker is not measured as RMS. You should check the specs of the Focals again.