This 300W OCL (ouput capacitor-less) power amplifier -i’m sorry for the blur diagram, but it shouldbe readable- use 4 pairs of 2N3055 dan MJ3055 transistor as the main power components. There are will be 8 pieces of them which should be attached on aluminium headsink. It’s will be better if you add small fan to blow the heatsink and transistors (just like fan and heatsink for computer processor).
This amplifier require dual polarity power supply with minimum transformer current output at 5A. And of course, with high power output, you also need good loudspeakers to make great audio output performance.