New sound card on amd64

[vr <debian-user@iotk.net>]

I'm using Debian unstable amd64 with an Intel DP55WB motherboard with
on-board audio.

I bought a replacement HT Omega Claro+ sound card with a CMI8788 chipset
because I'm after optical output to hook to a surround receiver.

I powered off my Debian system, inserted the new card, powered on and went
straight in the motherboard BIOS and disabled the on-board Intel sound
card.  Then I booted to Debian.

I've un-muted everything in alsamixer and set the volumes to 84.  The
"device" is seen and is set to C-Media CMI8788 in alsamixer.

I get audio out of the 1/8th inch jack ports but I cannot get audio out of
the optical port.

I did an apt-get update ; apt-get dist-upgrade (no errors).

I can successfully "speaker-test -Dplug:spdif -c2 with no errors, though
I'm not sure if that's completely accurate syntax to test the optical out.

Is there some other bit needed to make the optical port come alive?

Do I need to issue some command to flush remnants the old Intel drivers
out?