I'm a bit curious about the basics of how a amplifier works, and how it relates to speaker impedence, power consumption, decibels, and so on. I'm not in the market for a new amplifier, I just would like to have at least some grounding in electrical engineering, so as not to be lost in any future discussions, Some questions come to mind... First, I understand that a speaker-amplifier combination uses AC power, not DC. So, even if one were to assume that a speaker's impedance remains constant (not a wise assumption, perhaps, since everything is "nominal"), shouldn't one use something like the following? P=IV cos(phi) ? How does one calculate phi? Is it related to the frequency of the sound being generated? Or is it something else? How does a speaker's impedance change? How does a high current amplifier differ from an average run of the mill amp? What do the impedance switches found on some amplifiers actually do? Is there a benefit associated with designing a 4 ohm speaker over an 8 ohm device? And so on. To one group of persons, I may sound like a total novice. To another, I probably sound like someone who's worrying about the wrong things. Nonetheless, I'd appreciate some insight. Don't be afraid to break out the PDEs, either. I'm not a math novice. I'm just not an electrical engineer.