How could I connect two logitech z906 speakers to my PC?

The z906 is a 5.1 setup
surround-sound-speakers-z906-glamour-images.png


Are you looking to hook up two sets of these, or just two out of the bunch?
 


Competing/negating sound waves. For instance, the two subs will be putting out the same low-freq waves. Will probably sound very muddied.

More speakers != more/better sound, unless they are designed that way and are getting the correct signals.

Unless you are in a very large room, a single 5.1 setup is plenty. And if in a very large room, just adding another duplicate 5.1 setup off a typical splitter will sound like crap.
 


That depends on what you want to do, and what is lacking in the current setup?

Maybe a good quality sound card, maybe a better set than that Logitech, maybe a full standalone receiver and proper 5.1 setup (not PC speakers).
What do you perceive is lacking? How big is the room?

Just adding another similar 5.1 setup, powered from a so-so audio out on the motherboard, off a 3.5mm splitter, may make the thing sound worse.
 
Hmm,im not really sure,noting lacks with this setup,have it for like 6-7 months,but it just got boring and not loud enough for me lol, a sound card would not be a bad idea.
Heard its a different sound with one,which one would u recommend? And you were very helpfull,thank you very much :)