I don't know where you guys are coming from. But dynamic power is just a consumer euphemism for a technical term called peak value that mathematically is twice the RMS value. If there is an RMS value there is a peak value. And strictly speaking technically, there is really is no such thing as RMS power. What manufacturers put in their specs, at least those who are truthful in their specs, is CONTINUOUS AVERAGE Or MINIMUM power into so and so load. There are volts in RMS and current in RMS but never Power in RMS. But I can understand that RMS power has come to be an idiomatically accepted audiophile-speak for as long as we understand each other that it is continuous average, a value derived from an equation using RMS volts.
Using voltage or current measurements, an excellent amp can have peak values exceeding twice its RMS current or voltage values across a load. But depending on design and power measurements conditions, it can be far less. An amp measured at extreme but unrealistic conditions such as those from DIN into 4 ohms at 1% THD and with just one channel driven can yield numerically fantastic figures that leave little for peak power figures to be meaningful. They are effectivaly rating their amps in peak, not continuous average. Not conservative.
Powerful amps have filter capacitors with fantastic values to take care of peak voltage requirements, say 150volts and a total capacitance starting at 46,000microfarads and some in excess of 100,000 microfarads. These storage capacitors do not charge all the time unless they fall below a certain value and will discharge FAST enough to take care of instantaneous voltage requirements. Some designs use an array of parallel capacitors with smaller capacitances on the observed behaviour that small capcitance storage devices discharge and charge FASTER than large ones. Hence, rather than use double 23,000 mF caps, some would use eight 6,800mf caps instead to achieve a much faster response to transient current peaks.
Like I said PMPO is marketing hype that have no basis in technical terms, but real dynamic power is not. But because it has become an accepted fact that musical signals are dynamic, the ability of the amp to respond to such dynamic signals instantaneously requires some peak power abilities that has come to be called dynamic power or dynamic headroom to indicate in db the gap between continuous and peak.
It is true there are nor standards for measuring peak dynamic power. This had led manufacturers to use whatever measurement conditions and standards they want to arrive at impressive numbers that are sure to attract the uninformed customer. That applies to continuous power rating as well. But just the same, there are brands that do stick to CONSERVATIVE power rating, whether peak or continuous.
Another aspect of dynamic power is the ability of the amp to respond dynamically to impedance fluctuations that can go down to 2 ohms as presented to it by the speaker's own reactive load to different frequencies. A theoreticaly good amplifer doubles its available power as the load impedance is halved. This is indicative of the ability of the amp to respond dynamically to changing impedance across the audible spectra. Again, there is nothing hype about this. This is entirely technical and a very crucial quality of amp in the real world.
A typically complete power specs such as done by musical fidelity for its A308 amplifer goes something like this:
Voltage RMS: 35 Volts 20Hz to 20 KHz
Peak: 99Volts
Power: 150 Watts per channel into 8 Ohms (21.8dBW). 300 Watts per channel into 4 Ohms.
Peak-to-peak: output current 48 Amps
They don't give dynamic headroom or state the peak power in watts but indicate a more measureable value in terms of volts and amps.
In contrast, here's a NAD power specification for its T973 seven channel power amplifier:
7 x 140W Minimum Continuous Power (8 / 4 Ohms); all channels driven simultaneously
2 x 200W Continuous Power (8 / 4 Ohms)
230W, 390W and 450W IHF Power into 8, 4 and 2 ohms, respectively
Note that in both situations, the term RMS is never used. They're some of the few manufactuers who don't need to overstate their products' specs.
