Originally Posted by jlpowell84
Does anybody know the true RMS/continuous wattage when running all 7 channels? I read somewhere it's 67 watts/channel. And for example if you ran the MM7025 to your front L/R towers would it not also free up more power for the remaining speakers?
From Marantz glossary page:
70% Power Guarantee
Marantz has the 70% power guarantee, meaning that a minimum of 70% of the stereo power indicated in the specification section will be available when 5 channels are simultaneously used. A lot of misunderstanding about power rating has been created by claiming the highest possible output power as a unique selling point. Measurement often has been done on only 1 speaker drive, with lower impedance than 8 ohms and high THD (total harmonic distortion) acceptance. A standard THD value is 0.08%. The lower the better.
The url is here, just scroll down to the "70% Power Guarantee" paragraph:
Interestingly enough, on the SR5007 specs published on Marantz's UK site there is a clear reference to this "70% Power Guarantee", but there is NOT such note on the Marantz US SR5007 published specs. Marketing screw-up or real difference between US and UK versions of the SR5007???????
At any rate, depending on how the power supply has been designed, if on 5 channel the SR5007 is supposed to deliver at least 70W (being 100W the power on 2-ch), power output on 7-ch is probably going to be in the 55-60 Watts range (just my guesstimate).
For example, according to Home Theater tests, the SR7007 (the top of the SR line), which is rated 125W on 2-ch at 8 Ohm, measured at 90W on 5-ch (72%) and 71W on 7-ch (57%).
I would not get too obsessed about those figures, though. Although ability of driving all channels simultaneously at a certain percentage of the 2-ch power can tell you something about how beefy the power supply is, in real listening situation I see dynamic headroom as more important. That depends on a lot of factors, including speakers sensitivity, your preferred listening level, adding an external amp for the fron channel, settings of your sub-woofer and dynamic of the source you are listening to or watching.
Just my two cents.