OSX Mavericks (includes current Appleseed Beta release), latest Apple Java Update applied
When opening and closing a Chest of either size (note, I haven't checked with Ender Chests) the "Open" chest audio is played before the "Close" audio when done quickly.
1. Place a chest > Right Click to open chest
2. Observe "Open" Audio is played
3. Open and Close the chest in quick succession (sub 2 seconds from my playing)
4. Observe initial "Open" Audio plays, but on closing you hear both the "Open" then "Close" audio in quick succession
100% reproducible (I haven't loaded previous versions to check when this may have been introduced, but I have noticed it since 1.6, it's most likely older than that)