Frustrated by the lack of proper stereo panning in Ableton Live 9, I built a VST plugin for this explicit purpose. I know there are (convoluted) ways to achieve this in Ableton Live 9, but it’s all too awkward. I also know that this is fixed in Ableton Live 10, but I’m not ready to migrate to that version yet.
The plugin is described in detail here, and you can download it (plus other plugins) for free from here (for Windows only).
FlyLogical 