MOST amps that "double down" are simply under-rated at higher impedances for sake of advertising purposes. Most will do WAY more at 8 ohms before clipping than what their rated power specifies. This gives them what appears to be "high current" status and a high "dynamic headroom" rating also. Both tend to add to their status as being signs that the amp is built quite sturdy and able to drive tough loads.
As such, you can see why they might take a lower overall power rating simply for the "doubling down", "slam" and "tremendous peak power capability" that it would offer. If you look at the actual measured power at clipping with various impedances, you would see that the figures were "fudged" somewhere along the line though. The figure for 8 ohm clipping would not be too terribly far off from the 4 ohm point of clipping in many cases. At least not the expected 50% ( or doubling as impedance is halved ) as one might expect.
The exceptions to this would be the amps that come as close as possible to true "voltage sources". These amps basically DO double down ( or come extremely close ) at the point of clipping as the impedance is halved. I know that the Sunfire's ( verified in independent testing and reviews ) do this and i would think that the Innersound might ( not sure ) according to their claims. Some of the other digital based power supply amps might be in the ballpark also.
The bottom line is that you want an amp that has the highest rail voltages and the highest amount of sustained current capacity that can respond quickly. If that sounds like a mouthful and a lot to ask, it is. Even if you were to get all of those things in one amp, that is not to say that you would like the tonal balance or other aspects of the amp. There is a LOT more to building a balanced package than just being able to drive the speaker to high volumes and try to keep it under control. Sean
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As such, you can see why they might take a lower overall power rating simply for the "doubling down", "slam" and "tremendous peak power capability" that it would offer. If you look at the actual measured power at clipping with various impedances, you would see that the figures were "fudged" somewhere along the line though. The figure for 8 ohm clipping would not be too terribly far off from the 4 ohm point of clipping in many cases. At least not the expected 50% ( or doubling as impedance is halved ) as one might expect.
The exceptions to this would be the amps that come as close as possible to true "voltage sources". These amps basically DO double down ( or come extremely close ) at the point of clipping as the impedance is halved. I know that the Sunfire's ( verified in independent testing and reviews ) do this and i would think that the Innersound might ( not sure ) according to their claims. Some of the other digital based power supply amps might be in the ballpark also.
The bottom line is that you want an amp that has the highest rail voltages and the highest amount of sustained current capacity that can respond quickly. If that sounds like a mouthful and a lot to ask, it is. Even if you were to get all of those things in one amp, that is not to say that you would like the tonal balance or other aspects of the amp. There is a LOT more to building a balanced package than just being able to drive the speaker to high volumes and try to keep it under control. Sean
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