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Same watts at 8 and 4 ohms?

I'm in the market for an integrated amp and trying to sort through tech specs. My understanding of the tech aspects of hi-fi gear is limited. Looking for some clarity in regard to watts-per-channel specs.

It is my understanding that wpc at 4 ohms is typically 1.5x -2x the wpc at 8 ohms.

But I'm seeing a number of respectable mid-fi integrateds with the same wpc for both 8 and 4 ohms. The NAD 388 is one and I think this is true for several of the Cambridge Audio units at a similar price point ($1500-$2000).

The NAD features make a point of saying " 4-ohm stable for use with a wide range of speakers". 

Would appreciate any insight to what these specs mean and what 4 ohm stable really means to me. My speakers are 4 ohm speakers.

Thanks,

George
n80
djones51
4,947 posts
 
I imagine you feel 16Hz more than hear it. 
n80 OP
2,116 posts
 
I think you can see it. 
cakyol's avatar
cakyol
940 posts
 
Ideally, a power amp should be able to deliver twice as much power at half the impedance. The way it can achieve this is if:

1) Its power supply can meet the demand (probably the most important criteria).
2) Its output stage/heatsinks are designed to dissipate the demands of the extra power.
3) It is still stable with the higher load (less impedance).

So, if it is NOT able to do it, most likely one or more of the above is suspect. Most of the time, it is the power supply inadequacies (item 1 above).

dave_b's avatar
dave_b
3,159 posts
 
Amp should double.  More power is better.  Class A or A/B best.  Heavy is good.  All the aforementioned has never lead me astray!
atmasphere's avatar
atmasphere
11,807 posts
 
Ideally, a power amp should be able to deliver twice as much power at half the impedance. The way it can achieve this is if:
This statement is false, on account of the fact that list following it is not what is needed. What is important here is that the amp is able to act as a voltage source and to that end, it does not have to double power as the load impedance is halved- at full power. Any amp that has an output impedance low enough will effectively double power as impedance is halved, with the exception of when the amp nears clipping. That is the only time that doubling power might be an issue, and only important if you have a low impedance load and you really for some reason need that last 3dB, which is not a very audible increase to the human ear.

This 'doubling down' thing is mostly marketing and **waaaaay** overplayed.
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