Power is the product of the signal voltage * current * the cos(phase angle between them).
That cos term and the ability to act as an ideal source as the load impedance drops, is what makes most of the difference when it comes to balls.
The cos term varies between +1 and 0 as a factor depending on whether the load is completely inductive or capacitive, or something in between, at a given frequency. A purely resistive load will always be a factor of 1.
The impedance, usually simplistically thought of as 8 or 4 ohms, can often vary as low as 1 ohm or as high as 20 ohm, as a composite of resistance, inductance and capacitance.
A good indicator of the balls of an amp is if it can double its’ output power down to loads as small as 1 ohm. Most can’t.
Then there’s the concept of bridging or strapping an amp to make it a mono-block. In the case of bridging an amp, the two outputs are connected in series, out of phase, potentially doubling the voltage swing, but the same current capability, across the two pos terminals. This can result in a potential V**2/R power increase of 4x. Strapping places the two outputs in parallel, resulting in the same output voltage swing but with a potential doubling of the current capability. You might think that this could also result in an I**2*R 4x power increase but it doesn’t because the required voltage level can’t be met.
What this means is that in my opinion, the strapped output results in a much ballsier amp, able to easily drive difficult loads, than the bridging case. The BAT VK tube amps, and Accuphase A200 or A250 comes to mind. If you have a relatively easy load, the bridged case will likely provide greater volume or power levels but will peter out (current starved) if trying for the same levels with a difficult load loudspeaker.
That cos term and the ability to act as an ideal source as the load impedance drops, is what makes most of the difference when it comes to balls.
The cos term varies between +1 and 0 as a factor depending on whether the load is completely inductive or capacitive, or something in between, at a given frequency. A purely resistive load will always be a factor of 1.
The impedance, usually simplistically thought of as 8 or 4 ohms, can often vary as low as 1 ohm or as high as 20 ohm, as a composite of resistance, inductance and capacitance.
A good indicator of the balls of an amp is if it can double its’ output power down to loads as small as 1 ohm. Most can’t.
Then there’s the concept of bridging or strapping an amp to make it a mono-block. In the case of bridging an amp, the two outputs are connected in series, out of phase, potentially doubling the voltage swing, but the same current capability, across the two pos terminals. This can result in a potential V**2/R power increase of 4x. Strapping places the two outputs in parallel, resulting in the same output voltage swing but with a potential doubling of the current capability. You might think that this could also result in an I**2*R 4x power increase but it doesn’t because the required voltage level can’t be met.
What this means is that in my opinion, the strapped output results in a much ballsier amp, able to easily drive difficult loads, than the bridging case. The BAT VK tube amps, and Accuphase A200 or A250 comes to mind. If you have a relatively easy load, the bridged case will likely provide greater volume or power levels but will peter out (current starved) if trying for the same levels with a difficult load loudspeaker.