Designing an Audio Amplifier for a 9 Inch 25W Sub



I want to make a audio amplifier for a 9 inch 25W sub (no big deal), and I found a 40W power amplifier design using TDA2030AH and two transistors. As the following circuit show:

The datasheet of TDA2030AH:
It just employs only few components and does not require a dual power supply. Well,the circuit should meet the following conditions:
1).The circuit must be assembled on good quality PCB.
The PCB tracks through which there is high current flow should be made broader.
2).12V to 40V can be used for powering the circuit. For maximum output, use 40V supply and 4 Ohms speaker.
3).ransistors and IC must be heatsinked.
4).Input and output grounds must be properly decoupled for optimum performance.
I would like to ask that what the minimum current for the power supply? Is 2A enough? Has anyone made such a amplifier?

Best regards~