It sounds like you did some basic work, what I usually do is make sure aplay works. This usually means you choose the iec958 device listed with aplay -l, or aplay -L then pipe the content to the proper device. I also like to test with mplayer as well as you can tell it what device to output as well as test if your receiver is getting the proper lock, be it dts, or what have you.
Here is the sound howto which might be useful if you haven’t looked at it before. Also would not hurt to look at the intel-hda howto as well as that has more information about going into the kernel drivers and finding you setting so you can set up your modprobe.d sound file.