Hello,
only yesterday I put together my first Pi2 setup with Volumio, I use it primarily to stream music from NAS. I could get it all (2.1) running using jack on Pi, I was hoping to use my old USB sound card Xfi Surround 5.1 Pro though. After bit of tinkering I was able to make it play 2.1 as well but I have no idea how to get 4.1 I need out of it. I tried to exercise some Google-fu but being totally fresh in this whole Linux business I got hopelessly lost very fast.
Any advice, please?
Did I break some rule by posting this question? Did I miss an obvious answer while browsing the forum? Did nobody encounter the same issue? Or is it just because I admitted I don’t understand Linux whatsoever? 
As my Stone Age Cambridge Soundworks speaker system uses two jacks (front, rear) for input only, I can’t try a different means of connecting (DACs I have seen so far have either two RCAs or SPDIF connector), so I don’t even know whether it’s software, hardware or connection issue. Or do I miss something obvious like setting up Volumio properly?
googleing a bit and i noticed that there is no Linux support from creative, they made the driver open source for the community to do what they coudnt in two years. http://www.theinquirer.net/inquirer/news/1049476/creative-linux-x-fi-driver
Before it became open source it didnt even have ALSA support and the only platform it worked on was x64 and your R-Pi isnt. And i spotted a post over at ubuntu’s forum saying pulse audio worked better for him.
Take a look in this forum, it looks like they got it working on ubuntu you might learn something from it.
http://ubuntuforums.org/showthread.php?t=958330