After a number of dead-ends towards getting sound running on my desktop, I think it's almost there after the hard work of some of the linux kernel maintainers. Bug 55541 Bug 109191

The first bug is for the CA0132 DSP series of cards (Recon3D, Soundblaster Z). This fixes the DSP not working on x86_64 kernels. The second bug is specifically for the Soundblaster Z series of cards. This is not yet resolved, but it seems like there's active work towards fixing it.

Only downside to recent fixes is that there's no current support or patches in Debian 8 (yet). This means compiling a new kernel. I've chosen to run 4.4-rc5, but in the future non-RC kernels should be used (4.4+ should be good).

For reference, here's the steps to build a new kernel on Debian 8. DO NOT DO THIS UNLESS YOU KNOW WHAT YOU ARE DOING. YOU CAN BREAK YOUR INSTALL BY MINDLESSLY FOLLOWING THESE INSTRUCTIONS.

wget https://cdn.kernel.org/pub/linux/kernel/v4.x/testing/linux-4.4-rc5.tar.xz
mv linux-4.4-rc5.tar.xz /usr/src

A note here, due to my local setup I had to copy the source, set ownership to root:root and build as root. For regular users, having your own user own the source folder should be fine.

tar xvf linux-4.4-rc5.tar.xz
cd linux-4.4-rc5.tar.xz
cp /boot/config-3.16.0-4-amd64 .config
make-kpkg clean
make-kpkg --rootcmd fakeroot --revision=1.0.mmallin --initrd --jobs 8 kernel_image modules-image
cd ..
dpkg -i linux-image-4.4.0-rc1_1.0.mmallin_amd64.deb

Reboot at this point. Then you'll have to install an updated NVIDIA driver due to the kernel change. One last reboot later and you should be staring at your X desktop again.