RCA 1 Female to 2 Male Splitter?

Hi, i recently set up my speaker system, i am inputing from a Laptop to a Terratec Homearena 5.1 and using a male to 2 female splitter to split the jack into 2 inputs of which plug into the back of the Sub. However, due to this set up i can only have 2 speakers set up (Input F/R F/L, Output F/R F/L) Is there a way that i could output with more than 2 speakers? Such as using a 1 female to 2 male splitter so that the RCA cable splits into 4 inputs instead of 2? Sorry if this is unclear/hard to understand xD