[Brad Leigh] “Audio can be slid less then a frame with Quantize to frames on, as long as ripple is off and the audio event is not grouped to a video event or ignoreevent grouping is selected.I do it everyday. I was surprised to learn this myself. I believe John R said this may go as far back as version 8.”
This became an option in Pro 9.
From the Pro 9 Readme notes:
Audio-only edits (such as event moves, trims, and ASR times) are no longer quantized to frame boundaries by default when Quantize to Frames is enabled.
If you want to quantize audio-only edits, clear the Do not quantize to frames for audio-only edits check box on the Preferences > Editing tab.