The amplifier works on 12 Volts which may be tapped from inside the computer. A socket is fitted for connecting the speakers, and the input is fed in by a cable to be terminated in a stereo EP jack.
Step 1: Tpa1517 stereo amplifier
The chip, two large electrolytics, and three smaller capacitors will make the amplifier complete. I am adding an output socket too, on board. The input shall be via a stereo cable and there has to be a 12 Volt supply line, as well.
The picture is of the major components arranged on a blank piece of PCB.
Step 2: Populated board
The capacitors are connected with flexible wire taken from Hard disk flat cable, and so the input capacitors can move and short out. They shall be placed in position and encapsulated in hot melt glue.
Step 3: Ready for potting
If the regular epoxy potting compound is used, this won't be that easy.
A sort of enclosure is made by taping thick paper around the board, and the hot melt glue melted and flowed around the components using my hot air tool fitted with a narrow nozzle.