Multichannel whith Sound blaster Z

I am trying to playback multiple channels in Cubase 8 Pro. My SB Z 5.1 playback works fine in windows 8.1, but i can only get 2 channels in Cubase. I know SB is not the greatest card to use, but my Presonus Audiobox iTwo only have 2 channels. I just wanted to try if this is possible. Note that this is about playback, not recording.