VLC or Firefox bug w/SPDIF?

[jammnrose]

Running the latest (27-inch, Mid 2011) iMac here with 10.7.2, Firefox 8.0 (64-bit), VLC 1.1.12 (64-bit).

I have digital out (TOSLINK) connected. 'Use S/PDIF when available' is checked in VLC prefs.
I also have Perian 1.2.3 with 'Multi-Channel Output' selected (additional custom options through Terminal: $ defaults write com.cod3r.a52codec attemptPassthrough 1 and defaults write org.perian.Perian attemptDTSPassthrough 1).

My digital decoder has two lights depending on what sound source is being received:
Dolby Pro Logic IIx (this LED is on most of the time: normal apps, sounds etc)
Dolby Digital [presumably a 'Dolby Digital Plus' capable decoder, as it claims 7.1 surround] (this LED lights up (and is switched to) during video playback in VLC)

My issue is this: It seems like when I have Firefox running, S/PDIF passthrough does not work in VLC, though I have audio in other applications.
I need to quit Firefox before opening VLC. If I don't quit Firefox, I get no sound via VLC S/PDIF passthrough (my decoder light confirms this, as only the Dolby PL IIx LED is on).
If I quit Firefox, opening a video will cause my decoder to light up the Dolby Digital LED, and I get surround sound just fine.

Has anyone run into this issue before?
Narrowing it down to a conflict with Firefox took a little while, but this seems to be the case.

I am able to get Dolby Digital to play via MPlayerX (from Apple App Store) with Firefox running (decoder LED switches to Dolby Digital), so I'm guessing it's likely a small bug in VLC and not Firefox.

Thoughts anybody?