I have to say i didnt know DIN was a power rating, but i now know better!
'Root Mean Square (RMS) - this test can be deceptive, particularly for high power applications as the test is carried out at just one frequency at a time. This does not put a realistic demand on the driver compared to real life use and it is therefore very difficult to compare an RMS rating to a pink noise test.
A 100 Watt "RMS" amplifier can produce a 100 Watt sine-wave into its load. With music, the total actual power would be less. With a square-wave, it would be more.'
'The DIN 45000 defines different methods to measure power, depending on the device under test.
Power measurement of an amplifier requires that it is properly terminated by Ohmic resistances of nominal value both at input and output. The continuous power is measured when the amplifer is supplied by its normal power supply. It must then be able to deliver the rated power at 1 kHz for at least 10 minutes while the maximum THD does not exceed 1 %. To measure the peak power the normal power supply is replaced by a regulated power supply and the time for delivering the power is reduced. Thus, higher values for peak power are obtained. You may skip measuring the peak power by simply multiplying the continuous power by 1.1.
The power bandwidth is defined as the frequency range for which 1/2 of the rated continuous power can be obtained.
DIN 45 500, CNF 97-330, EIA RS-426 and the encompassing IEC 268-5 specify not pink noise, but pink noise filtered by a filter that provides significant attenuation in the low and high frequency region of the spectrum to more closely model the long-term spectral distribution of music. Pink noise itself does not accomplish this.'
Ok, so since im learning i'll explain to my best undersatnding. RMS actually quantifies the power. DIN (as i thought) is not actually a power measurement, rather it is a specification. So I guess power is measured by RMS, then if it can supply the rated power at 1 kHz for at least 10 minutes while the maximum THD does not exceed 1 %, then it will get a DIN standard spec at that power. That is a guess though.
The site i got that from is http://www.stagetec.co.uk/SOUNDPOWER.htm It interests me because I always thought that RMS was the most accurate measurement, but clearly it isnt. I wonder how many manufacturers quote the most accurate IEC power?