Here's why:

* Voltage: Speaker wire is designed for low voltage signals (typically less than 100 volts) and low current. Amplifier power cords carry high voltage (typically 120 volts or 240 volts) and high current. Using speaker wire for power would be extremely dangerous and could result in electrical shock, fire, or damage to your equipment.

* Gauge: Speaker wire is usually thinner than power cords. This thin gauge is suitable for the low current signals but inadequate for the high current demands of an amplifier. The wire could overheat and melt, causing damage to your amplifier and potentially creating a fire hazard.

* Insulation: Speaker wire insulation may not be rated for the high voltage found in power cords. This could lead to short circuits and electrical hazards.

* Connectors: Speaker wire ends are typically bare or terminated with banana plugs or spade connectors, not designed for power connections.

In short, using speaker wire for power is a very bad idea. Always use the correct power cord provided with your amplifier or a specifically designed replacement.