Yeah, definitely not on Perian's supported list. I would suggest it as a possible addition by e-mailing the Perian team, but in the meantime it looks like you're stuck with VLC for that one.
EDIT : However, having had a quick Google this may help.
EDIT 2: A bit more Googling adds in some extra detail. Apparently the A52 IS supported as part of the AC3 support in Perian 1.0. Are you using the latest Perian version (1.0) or are you on 0.9?