Darth Id said:

I certainly hope they're not doing a new sound mix for a purported "OUT".

More likely taking footage for a demonstrative special feature for Episode VII that will compare/contrast OT and ST techniques/technology.

This early?

I'd say this is either for a new SE or they're getting the audio just right for the OOT.

Or could they just be tweaking the existing 2011 audio for this rumored digital release?

Speaking of which, if the digital release is in November it would make sense that we haven't heard an official announcement just yet.