So is the "1w/1m" important if your amp is 200 wpc?
Probably not as much to a degree. However, the higher the sensitivity the more headroom you will have available from the amplifier at normal volumes.
Example Time!
For instance say at a moderate volume level you are averaging 25 watts of output from the amplifier. The speaker you are using is 94db 1w/1m. you sit 15 feet from the speakers which would decrease that 1 watt output to 80.5db at the listening position.
Because you have two speakers (unless you listen in single channel mono
) and two channels of amplification, you are doubling the surface area and power resulting in a theoretical gain of +6db to the baseline output at 1 watt, resulting about 86.5db at the listening position. Quite loud for a single watt of input.
Since you are averaging 25 watts of output, the volume at the listening position is actually around 100db. If you are listening to a dynamic recording you will have 9db of dynamic range available with 200 watts rms on tap before clipping of any sort. This yields a peak output level of 109db.
Let's say you swap speakers and they are only 90db 1w/1m. Again, sitting 15 feet away with 1 watt of output, the level would be 76.5db. Add in the other speaker and amp channel and you are at 82.5db. At 25 watts continuous output you would have a volume of only 96db and a peak output level unclipped of just 105db.
To get the 90db speakers to the same average level, or close to it, as the 94db speakers, requires and extra 25 watts continuous of amplifier output decreasing available unclipped headroom to just 6db.
To achieve the same level of dynamic capability and continuous output level you would now have to have a 400w rms amplifier.
This is not a big issue as 100db average volume is very loud. However only having 9db of dynamic range is not a lot. Take a recording like Dire Straits' "Brother's in Arms" with average dynamic range on the record in the 16db-18db range and you are asking for slightly clipped top end when listening at that level. You would have to lower the overall (average) output level to around 4 watts rms or 92.5db so as not to have any clipping in the dynamic range on a 200 watt rms amplifier with the 94db sensitivity speakers.
This is why we typically hear people saying bigger amps sound better. It is about DYNAMICS. To listen at the same levels listed above (for the 94db speakers) and have totally unclipped dynamic playback, one would need a 800-1600 continuous watt per channel amplifier. Obviously, it is not typical to listen at such high volumes nor is it recommended. A 400 watt rms amplifer would work in nearly all cases for distortion free playback at moderate to high levels with little to no clipping at the distance of 15 feet from the speakers. Any that would occur would be inaudible.
This is why you see some users who feel that receivers are inadequate for power. They simply will not have the unclipped dynamic capability for speakers with lower sensitivity.
This is a bit off subject though as far as the intent of the post is concerned. However it is somewhat relevant. The lower the speaker plays the more power consumed. Thus, the chance that a high continuous power level will be achieved or needed.
Hopefully this is not confusing.
