The power amplifier is indeed very simple, but no doubt the sound quality produced. Mid-low sound output character is very suitable for indoor or outdoor. For Outdoor try using Transformer 20A 45Vct, tr final 5 sets/channel using Sanken 2SC2922 / 2SA1216, which can produce up to 400W - 800W stereo power output. To generate maximum output power you should use high-quality components. Below the circuit diagram of mono power amplifier 400W using the Sanken Final transistor.
Power Amplifier Schematic
Component List Mono
TR2=TIP31/ D381/ D382
TR3=TIP32/ B536/ B537
TR4=TIP31/ D381/ D382
Power Supply circuit you can use minimum voltage 25Volts up to 45Volts DC CT (Symmetrical), the Power amplifier is introduced and manufactured by Saturn Electronics Indonesia and you can also see some of its products there. For those of you who are interested to string up, make my own PCB Layout provide for you, PCB layout is designed by Saturn Electronics Indonesia.
PCB Layout Power Amplifier 400W + 400W Stereo
Assembling Super Power 400W Driver VIDEO
TESTED VIDEO Power Amplifier 400Watt by using 2SC5200 and 2SA1943