Thank you, Rogue Leader.
And this one? Did it works?
https://www.amazon.com/E-More®-Ouality-Digital-Optical-Surround/dp/B00Q4KYW5E/ref=sr_1_4?s=aht&ie=UTF8&qid=1473260270&sr=1-4&keywords=optical++to+5.1
I have the same speakers Logitech and I used this convertor. I conect the optical cable from Tv in optical input of adapter. In the other side, I plug the white and red cables from the subwoofer.
http://www.amazon.com/dp/B01AWBA8U8?psc=1