The 10 W Power amplifier circuit diagram, based on the application note from SGS-Thomson, suggests the relative simplicity of this achievement. And that’s mainly what made the TDA2003 is popular (according to the TDA2002, a little less powerful but you can use here without changing anything else in the components).
Speaker impedance and output power
You can use an speaker or a combination of speaker with a value between 2 and 8 ohms. The power of 10 W for 2 ohms specified (2 speaker 4 ohms connected in parallel, for example) will decrease if you choose an speaker impedance higher (in the case of all the audio amps). For Power supply 18 V.
With 1.6 ohms: 12 W to 10% distortion – 9 W 0.15% distortion
With 2 ohms: 10 W to 10% distortion – 7.5 W for 0.15% distortion
With 3.2 ohms: 7.5 W at 10% distortion – 5.6 W for 0.15% distortion
With 4 ohms: 6 W at 10% distortion – 4.5 W for 0.15% distortion
With 8 ohms: 3 W – but the TDA2003 has not really been designed to work with a load as “high”.