
The SPL level at a distance is measured by the loudness, or DB level, which decreases on a logarithmic scale with increasing distance. Thus, my 600 watt system can produce 135 dB, whereas yours might only produce 130 dB.
Simply put, speakers labeled at 500 or 800-watts are rated for the highest power they can manage. With these speakers, a lower power amplifier can always be used. Observe that at a distance of one meter and a sensitivity of 98 dB, it is the maximum volume they could produce.
If your speakers are 90dB efficient and you enjoy listening to loud, uncompressed music, 200 Watts should be more than enough power for you. 50 Watts is plenty if all you listen to is jazz and light classical music and you don't need them to blow you away. Like horns, speakers with higher efficiency consume extremely little power.
Large touring sound companies frequently use 80,000 to 400,000 watts altogether, even though an arena rock event could only need 15,000 watts (leaving only 6 dB of headroom for peaks).
What Digital DJ Tips Says:If the performance is indoors, you should, as a general rule of thumb, try to have at least five watts per participant. That should probably be doubled, to 10 watts per person, if you are playing outside or want to [rave volume].
People's eardrums will pop at 700 watts, and the wall plaster will fall out.
Recognize that a 30 watt speaker is not designed for extremely loud music and refrain from raising the volume up to the point where it becomes distorted. In most households, 5 watts to a speaker is actually rather loud. It should be sufficient to play music in a satisfactory manner without putting the speaker in danger of damage.
To save your hearing, keep the level between 70 and 75 dB. Over 85 dB is considered harmful for human hearing. Furthermore, noise levels beyond 130 dB are deemed uncomfortable.
Although a 100 watt bass amp will drive the speakers loudly and satisfactorily, it will be straining its limits to do so.
Tips for masteringAim for a -14dB integrated LUFS loudness level for your master, and maintain it below a -1dB True Peak maximum. This ensures that no additional distortion is generated during the transcoding process and works best for lossy formats (Ogg/Vorbis and AAC).