We have found one software suitable in our database for this conversion.
Both .vss (smartshape) and .vsx (stencils) files originate from Microsoft Visio and it is likely that only this program can work with these formats reliably.
If you need to convert vss to vsx or vice versa, Visio remains your only viable choice as no 3rd program is most likely capable of vss to vsx conversion.
Updated: February 23, 2017
A diagram application, that uses vector graphics to create diagrams. Microsoft Visio is distributed as part of Microsoft Office Family and also available as a subscription through Microsoft Office 365. The latest version is Visio 2016 that is compatible with Windows 7, Windows 8 and Windows 10.