The datasheet for the Sony stereo amplifier IC is a horrible translation that is missing the supply voltage for the power vs distortion curve, and its output shows mV instead of mW. If it is 6V then the output power (?) at clipping is only 0.2W into 8 ohms per channel, exactly the same as an LM386 amplifier.
Its max distortion is a terrible 2.5% when the output is only 0.05W and is probably higher at a higher output power.
It was made for a cassette player (remember?) so maybe it is not made anymore.