Today’s word was a special request from an inSync reader who has been seeing it used on line a lot lately. PMPO: Abbreviation for Peak Music Power Output. A very subjective specification designed to help provide “real world” wattage ratings for power amps and speakers. Lots of number games are played with specifications and very few are held to specific and rigid testing standards. Consequently their value in comparing equipment is often less than ideal. Further, many specifications are obtained in lab conditions that don’t translate easily to how the device is likely to perform in the real world, which adds more confusion. For example, power amps are often tested with sine waves, pink noise, and other non-musical signals. These signals can be very demanding (in different ways) for the equipment to reproduce, whereas a “typical” music signal is much easier. The purpose of PMPO is to show a product’s performance in real world circumstances that are allegedly more meaningful to the user. An amp that may not compare very well in lab tests to a much more expensive model will often show up as much closer in terms of PMPO. Proponents say this puts the specs on paper much more in line with the actual audible difference in the products. Unfortunately the PMPO measurement is far more subjective than most specs because, in addition to the ambiguities many specs suffer from, there is no standard for what “music” means. Ten different manufacturers can still test their product under ten different sets of circumstances. PMPO is mostly used in the consumer hi-fi industry where deep understanding of specifications is often not a concern.