I just got Logitech Z680's for $40! What mode do I use for the wii?

[blackbird3216]

I got them for $40 from a guy on craigslist, but i can't seem to get Dolby Pro Logic II to work on the wii. When i switch the effect to DPII movie, it gets really quiet. Do i have to have a direct connection to the speakers? BTW, my rear speaker cables are too short. What cables do use to extend them?

Out of the following modes, which is the best for the wii?

DPII Movie

DPII Music

Stereo

Stereo x2

Direct

http://www.amazon.com/Logitech-Computer-Speakers-5-Speaker-Silver/dp/B00007AKDP