Here is a simple rule of thumb. Sensitivity of speakers is in dB/watt at a particular imoedance e.g. 8 ohm.
For every increase in 3dB, you need to double the power of your amp in watts.
E.g. Say you have a 91dB/w speaker. This means this speaker will putput 91dB at 1 watt and at 1 meter distance. To get 3dB additional output i.e. 94dB, you will need 2 watts. For 96dB, you will need 4 watts and 99 dB, you will need 8 watts etc.
Of course, you also have to look at the speakers impedance as this will vary with frequency. A speaker that drops to 2.ohm at low frequency will often sound bass light because SET amps usually have trouble driving below 4 ohms which mean that the power from the amp drops with low impedances.
For every increase in 3dB, you need to double the power of your amp in watts.
E.g. Say you have a 91dB/w speaker. This means this speaker will putput 91dB at 1 watt and at 1 meter distance. To get 3dB additional output i.e. 94dB, you will need 2 watts. For 96dB, you will need 4 watts and 99 dB, you will need 8 watts etc.
Of course, you also have to look at the speakers impedance as this will vary with frequency. A speaker that drops to 2.ohm at low frequency will often sound bass light because SET amps usually have trouble driving below 4 ohms which mean that the power from the amp drops with low impedances.