Magfan - No, lower voltage doesn't make for higher current draw (it happens in SMPS) but only limits max peak power. Amp in a sense is a regulated supply that delivers required (at given moment) voltage to the load (speaker). If it runs out of available supply voltage it will start clipping. If you don't use whole available power then line supply voltage change won't affect you.
What amp takes from mains is completely different story and depends on type of amps. For class A amps it will be constant current while for class B it will be just a few percent of max rated power of an amp. The reason for that is that music has very low average value and scale is logarithmic. When sound level is at 1/2 of max loudness amp takes 1/10 of max power.
Linear power supply takes current from the mains in very narrow spikes of high amplitude. It is in a sense SMPS that operates at 120Hz. Width of the spike depends on the current demand but also on output impedance of transformer and ESR of capacitors (Schaffer diagrams). It is called conduction angle. Because of that transformer has to be oversized (RMS power required is much higher than average power taken + high frequency content is heating the core) and power supply wiring and cords have to be oversized to avoid drops.
Linear power supply is therefore pretty noisy outside and using shielded power cables is needed.
What amp takes from mains is completely different story and depends on type of amps. For class A amps it will be constant current while for class B it will be just a few percent of max rated power of an amp. The reason for that is that music has very low average value and scale is logarithmic. When sound level is at 1/2 of max loudness amp takes 1/10 of max power.
Linear power supply takes current from the mains in very narrow spikes of high amplitude. It is in a sense SMPS that operates at 120Hz. Width of the spike depends on the current demand but also on output impedance of transformer and ESR of capacitors (Schaffer diagrams). It is called conduction angle. Because of that transformer has to be oversized (RMS power required is much higher than average power taken + high frequency content is heating the core) and power supply wiring and cords have to be oversized to avoid drops.
Linear power supply is therefore pretty noisy outside and using shielded power cables is needed.