Here is a 35W audio amplifier circuit built based on single Amplifier chip STK082. This is a very simple amplifier, very easy to build and produce sound output with a fairly large power of 35 watts into 8 Ohm loads.
This amplifier circuit is suitable for home power audio devices. The STK082 amplifier specifications might lead you to believe that it can use supply voltages of up to ±43V. but I don’t recommend anything greater than ±25V if 8 ohm loads are expected, although ±30V will be fine if you can provide good heatsinking.