Editing Audio power (section)

===Total system power===
'''Total system power''' is a term often used in [[Audio engineering|audio electronics]] to rate the power of an audio system. Total system power refers to the total [[Energy consumption|power consumption]] of the unit, rather than the power handling of the [[Loudspeaker|speakers]] or the power output of the [[amplifier]]. This can be viewed as a somewhat deceptive [[marketing]] ploy, as the total power consumption of the unit will of course be greater than any of its other power ratings, except for, perhaps, the peak power of the amplifier, which is essentially an exaggerated value anyway.{{citation needed|date=December 2011}} [[Shelf stereo]]s and [[surround sound]] receivers are often rated using total system power.

One way to use total system power to get a more accurate estimate of power is to consider the [[amplifier class]] which would give an educated guess of the power output by considering the efficiency of the class. For example, [[class AB amplifier]]s can vary widely from 25% to 75%[http://www.rockfordfosgate.com/products/details/t400-2] efficiency while Class D amps are much higher at 80% to 95%[http://epsilonelectronicsinc.com/news/2015/08/11/soundstream-is-now-shipping-stealth-124-marine-amplifiers/]. An exceptionally efficient Class D amp, the [[ROHM]] BD5421efs, operates at 90% efficiency.<ref>{{cite web|url=http://www.eetasia.com/ART_8800464222_499501_NP_c0bbb082.HTM|archive-url=https://archive.today/20120730184544/http://www.eetasia.com/ART_8800464222_499501_NP_c0bbb082.HTM|url-status=dead|archive-date=2012-07-30|title=Class-D amplifier guarantees 90% efficiency|date=2007-05-14|website=EE Times-Asia|access-date=2016-04-22}}</ref>

In some cases, an audio device may be measured by the ''total system power'' of all its loudspeakers by adding all their peak power ratings. Many [[home theater in a box]] systems are rated this way. Often low-end home theater systems' power ratings are taken at a high level of [[harmonic distortion]] as well; as high as 10%, which would be noticeable.<ref>{{cite web|url=http://hometheater.about.com/cs/audiocomponents/a/aapowermada.htm|title=Don't Get Seduced by Amplifier Power Specifications|website=About.com Tech|access-date=2016-04-22|archive-date=2016-05-13|archive-url=https://web.archive.org/web/20160513004005/http://hometheater.about.com/cs/audiocomponents/a/aapowermada.htm|url-status=dead}}</ref>