Setting the impedance Setting correctly is important

Always follow the manufacturer's instructions and set the amplifier to match the speakers

Your amplifier can only deliver a finite amount of power, so if you decrease the impedance, you will demand more current and the amplifier may struggle and may overheat and fail.

My Q Acoustics speakers specify the following.

Nominal Impedance: 6 Ohm (This is the preferred setting)

Minimum Impedance: 4 Ohm (This will provide more power)

When you lower the impedance the power will increase and put more demand on the amplifier. This does not change the quality of the audio produced, it just changes the amplitude of the waveform. Power =Voltage * current

Some Amplifiers have an impedance selector switch. This reduces the voltage that the amplifier produces, thus reducing the output power and current to a safe level.