Subwoofer hook up from PC to Focal XS PC Speakers

HI Everyone
How to hook up subwoofer from computer. Is this only way
1/8 from PC to L/R RCA input on subwoofer and from L/R
subwoofer output to RCA L/R on Satelite speakers. Will this
degrade the sound. Thanks
The answer is dependent on the quality of the crossover in the subwoofer but I suspect that, in the case of using a 1/8" ouput from a typical PC, it will not be significant.

If you were using an external, high-quality DAC, I would have greater concern. In that case, the better but costlier route would be an external crossover.