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
@atmasphere "There's a recording of the Saint Saens Organ Symphony on EMI that has 16Hz pedal tones."

I've got the Telarc recording. I have no idea how low does it go or how low my system limbos, but when that organ blasts through my Aerial 7Bs, the house rumbles and you feel it in your chest even at moderate volume.


I might have to see if I can get a copy of the EMI CD.
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).

Amp should double.  More power is better.  Class A or A/B best.  Heavy is good.  All the aforementioned has never lead me astray!