SID 6581 & Speakjet Chip

I want create a circuit with a SID6581 and a Speakjet chip. Is it good enough to combine the audiooutputs from both chips ?

You mean by having each go thru a resistor (to keep each from impacting the other), and the junction on the other side going into an op amp or something? Yes, that should be doable.

Are 200Ohm resistors good enough for the job ?

Maybe - what is the voltage swing of the 2 outputs, and do they have enough current output capability? current out = Vout/resistor value. So if they went +/-5v, with 200 ohm they'd need to be able to drive 25mA. If you're summing with an op-amp, I would go higher, keep the current required down.

If you do some googling on "audio summing circuit" you can find discussions like this:

So it really comes down to how strong the two source drivers are.