The mainboard I use provides header pins for getting the audio signal from inside the case (as opposed to the external Audio/Video connector)

However, this only works if real SID chips are installed. Wirhout these, the board provides FPGA simulation, which isn‘t bad at all. But still, no internal audio without soldering without real SID chips.

This is why I decided to put SID chips in. 

I‘m still waiting for the amplifier to arrive, but first test revealed they work great. 

One chip would be sufficient, but hey, it‘s all or nothing :-)