This post explains for the Amplifier.
The Part Number is STK4141, STK4141II.
The function of this semiconductor is 2-channel AF Power Amplifier
Package: ZIP Type
Preview images :
This is 25W min, 2-Channel AF Power Amplifier. This is thick film hybrid IC.
1. Smaller-sized package as compared with the STK450 series
2. Built-in muting circuit to cut off various kinds of shock noise
3. Greatly reduced heat sink due to case temperatue 125°C guaranteed.
4. Excellect cost performance.
1 page ( Equivalent Circuit )