[lunkhound]

I'm not sure if this will work for you if you have the same issue I do.
I am unable to get optical audio out to work if I do not have an HDMI
display connected. You can refer to my previous post on how I am
not able to get optical audio out to work with a DVI monitor (using an
HDMI to DVI adapter), but I also figured out that it would fail with no
display connected. So, in short, no HDMI display connected, no audio
out through optical.

Actually I've been able to get optical audio out without an HDMI display connected. It seems that connecting to the HDMI switch in my AV receiver (with no display device attached) is enough to satisfy the FTV. The AV receiver needs to be powered on for this to work, however.
I've ordered a cheap (less than $10) standalone HDMI switch to see if that will also work. A passive switch won't work, but an active switch MIGHT work. An HDMI repeater might also work. I expect to have the switch tomorrow, I'll report back when I've tried it.

If your $10 option works, please report back, as I am not sure which of the many options to try. I'd like the first one I buy to work. ?

Sadly, the cheap HDMI switch I bought didn't work (for my purpose).
It was a "Portta PET0301S 3x1 HDMI Switcher with 3D Support - No power supply needed". So I don't recommend that one!
On the positive side, the FTV was able to power the HDMI switch via its HDMI output. That means it should be possible to find a switch that works without needing its own power cord.
So to recap, plugging the FTV into an HDMI input on my Denon 3311ci AV receiver (with no display attached) allows the FTV to output audio on SPDIF optical. Plugging the FTV into this cheap HDMI switch did NOT allow SPDIF audio.