This post explains for the amplifier.
The Part Number is STK402-071, STK-402071.
The function of this semiconductor is 2 Channel AF Power Amplifier.
The package is Zip 15 Pin Type
This is 2 Channel AF Power Amplifier.
Absolute maximum ratings ( Ta=25°C )
1. Power Supply Voltage with no signal : Vcc = ± 50 V
2. Power Supply Voltage : Vcc max(1) = ± 44 V
3. Junction Temperature: Tj = 150°C
4. Operating Substrate Temperature : Tc = 125°C
5. Storage Temperature: Tsg = -30 ~ +125°C
1. Audio use
All tests are measured using a constant-voltage supply unless otherwise specified.