one cant be specific in this recard since u never know whats ur amp is pumping out, but rule of thumb in hometheatre amps, its like u never go pass 12 oclock position, that around 50% RMS (thou RMS is not linearly scatered over the scale ). same goes for speakers u never power them with more than 50% RMS rating, in this way all the peak output scenes stay in RMS zone of both amp and speaker.car audio is usually driven harder than home audio. so u can go above 50% mark if u wont more output.
if u look at non branded amp ratings, most of them rate there peak out out with lots of distortion , at 1Kz or more ( easy load ), single channel driven, ( which too are overstated). 1000w amp will hardy be making 100w rms with no audible distortion, but who cares becuz for normal listening u wont be using more than 10w for "normal" listening. as far as ur getting the dynamic range ( open sound ) without distortion, figures are next to nothing. not a specific answer but still to mate 1000w amp, one should have around 200RMS woofer
a cutting from net
Did you know that it's possible to damage a high power-handling speaker with a modest-powered amplifier in the 25 to 50-watt range? The following are simple steps you can take to ensure that your speakers will provide many years of enjoyment without need for repair.
Match amp power to volume preferences. Strange as it may seem, too little amplifier power can damage a speaker when combined with a listener's taste for high sound pressure levels. Within reason, there is nothing wrong with listening to your favorite song at live volume levels. In fact most manufactures create their speakers to do just that. But you can't expect a low-powered amplifier to do the job well. At some point, the amp will run out of "steam". Turning the volume control further up can cause clipping distortion. If you like to play your music at live levels for extended periods of time, you may want to consider purchasing an amp that has a power rating equal to your speakers maximum recommended power handling. This will avoid clipping, which can quickly damage your tweeters.
Avoid audible distortion! No matter what size or quality amp you are using-and no matter what volume you are listening at-don't turn up the amp to a point where you hear clipping distortion! What does this clipping distortion sound like? Most people agree that it sounds like the sounds are crackling, straining, or breaking up. If you have turned a small portable radio all the way up, you will know what I am talking about. Turning up a low-powered systems volume control too far is one way of causing audible distortion. Another way is to add excessive bass tone control. Bass requires the vast majority of an amplifiers power to start with; boosting bass excessively can quickly exceed the amps ability to deliver power to the speakers, even if you keep the volume level low. For example, a 3db increase in volume is barely audible, but requires TWICE the amplifiers power. Many tone and loudness controls can create a 10-15db boost, resulting in great demands of the amplifier, some of which may be impossible for the amp to deliver. To avoid clipping distortion, add tone control equalization in moderate quantities. If you do hear clipping from any of these reasons, turn down the volume and/or use an amplifier with significantly more power. Remember amp power must be doubled to produce an audible 3db increase in loudness. However a 200-watt amp will not drive a given speaker four times as loudly as a 50-watt amp. Instead, because amp power must be doubled to produce a 3db boost in sound, a 200-watt amp will only add 9db of added volume. To double the loudness of the sound, you must increase the level by 10db. This is equivalent to multiplying the amplifier power by 8!
Digital sources While avoiding clipping distortion is merely a matter of listening to your speakers sound quality, there's another kind of distortion that is much harder to detect. It can occur when playing music from digital sources such as CD's, MP3's, Mini Discs etc. at moderate to high volume levels. This is called transient intermodulation distortion (T.I.M.). Interestingly enough, T.I.M. distortion can occur because of the digital recordings excellent dynamics. A compact disc is capable of reproducing extremely short musical peaks , which are present in live music. These brief split-second bursts of much higher volume are called transients. They enhance the music by creating realistic "attack" or "punch" to the sound. However, they can also tax your amp by making momentary high demands of power the amplifier may not be able to reproduce. The result is a short burst of high frequency distortion that can tax your speakers tweeters even at a seemingly moderate volume. This doesn't mean that you must keep your volume level set low when listening to digital sources, however it does mean that at any given volume level, your amp may be asked to work harder. If you don't have an amplifier rating equal to your speakers maximum power, avoid the temptation to crank the volume all the way up. While discussing digital sound sources, remember that they have a wide audible dynamic range also. That is, the sound can start out soft and get very loud later into the song. This sudden increase in volume can lead to amplifier distortion. If you are about to play a CD, it is wise to listen to it the first time at a slightly lower volume, just incase it contains any sonic surprises.
Overpowering speakers I put this one last because damage to speakers is rarely caused by too much power. Still it can happen. If you hear strange sounds coming from your speakers, such as cracking or popping sounds, you may be bottoming your woofers. In other words, so much power is being applied to the woofer that its voice coil is actually being forced to its outer limits. This can cause damage fast! Back off the volume or reduce the amount of bass that is being sent to the amplifier. Clipping a bass note can sound very much like a bottoming a woofer with some amplifier designs. This is why some amplifier manufactures have what is called a "soft clipping design". This circuit makes it less obvious that the amp is clipping, giving you better sound at "the edge".