Naim 5si operating power consumption 300 w
Marantz 7010 power consumption 750w
Two channels driven, with crossover to sub, Marantz power should be more than sufficient. Most of us would scoff at Marantz when compared to Naim for two channel audio.
Is there more to it than power supply too ?
The 750W power consumption is also for 9 channels of audio. You need to look at the power it can deliver in 2 channels.
- Looking at the SR7010 specs:
- There are no specs at all for "all channels driven"
- Power output for 2 channel driven is 125W at 0.05% distortion level
- Power output at 6ohms is 165W but the distortion levels are already climbing at 0.7%. Plus, they're measuring this only at 1KHz and have given up measuring this for 20Hz-20KHz unlike their 8ohm rating
- They are able to squeeze out 235W of power at 6ohms, but alas, only when 1 channel is driven, i.e. mono audio. And distortion levels are now a whopping 10% which is basically garbage levels of distortion
- They have no specs at all for 4 ohms, which strongly indicates that the power supply does not support 4 ohm loads at all, even when only 2 channels are drive. Note that even many 6 ohm nominal rated speakers (or even some 8ohm speakers) routinely dip down to 4 ohms. You can take a look at Stereophile impedance curve measurements for most speakers.
So the 750W power consumption is irrelevant when the amp clearly struggles to even supply anything exceeding 125-150W of power per channel and lowering impedances even to 6ohms is really causing it to struggle. In short, it is the power supply implementation
per channel that is really important to determine.
The Naim is light on specs, but it is interesting that the amp is able to draw 300W of power from the wall, but its rated power is only 60W at 8ohms or 120W total for both channels (at 8ohms). Mind you, the 300W is reserved exclusively for 2 channels as it has no additional channels to supply power to. This indicates that if it is rated to supply 120W of power at 8ohms, and if its power supply capacity is 300W, it actually has more than enough headroom to double its power output from 120W to 240W if the speaker dips to 4ohms. So even after perfectly scaling up 2X power at 4ohms, it still has some headroom of additional 60W to support even slightly lower impedances. Some speakers like Dynaudio (or Totem like I used to own) do indeed dip down to about 3.6 - 3.8 ohms.
If anything, the specs indicate that the Naim is an amp with an exceptionally well built (or overbuilt) power supply.
Edit: I also realized that the Naim ratings of 300VA or 300W is only for transient loads and not sustained loads. So perhaps the power supply is not as exceptionally built. On further reading, it also looks like its actual official rating at 4 ohms is 90W and not perfect scaling of 120W. But this 90W is actually a downplayed number and also importantly, the distortion levels are also very low even at these peak levels. As per actual measurements, it really supplies 115W or so of reasonably clean power at 4 ohms. 110-115W per channel at 4 ohms is actually close to near perfect 2x power supply scaling - at least based on the 60W official specs (and not the 75W that it actually is able to deliver per channel at 8 ohms).
There are other parameters that are important too, of course, like channel separation. But I wanted to keep it simple, as I personally feel the power supply strength often indicates a lot of things - the amount of engineering and design and focus that went into it, and consequently the amount of attention that would have gone into other important amp parameters as well.
Even for DACs, I feel that the chip and filter and topology and all that takes a back seat to the power supply implementation quality and robustness. Again, my personal thoughts, I am no expert by any means.
Please see
this article for the detailed analysis.
Excerpt:
Even with both channels driven, the NAIT 5si comfortably exceeded its specified maximum power outputs into 8 ohms (fig.5) and 4 ohms (fig.5). At our standard definition of clipping (ie, when the THD+noise reaches 1%), the Naim clipped at 76Wpc into 8 ohms (18.8dBW), a full dB above the specified 60Wpc. Into 4 ohms, the NAIT clipped at 115Wpc (17.6dBW), more than a dB higher than the specified 90Wpc.
Read more at
https://www.stereophile.com/content...ed-amplifier-measurements#gb8C7pE7fQqyqkxp.99
