I've found a workable work-around to the problem of Express Scribe failing to recognize any of the files produced by the Olympus DS-2. I downloaded "EasyWMA", a shareware program for the Mac that converts WMA files into MP3's. MP3's are equal in size to the WMA files and they are recognized and loaded by Express Scribe. Aside from the extra step and the long time required for conversion, this is workable.
The solution is not perfect, however, because the WMA files are only produced by the DS-2 when it's in HQ (mono) mode, or either of the two stereo modes. The DSS files that the DS-2 produces (in SP and lower quality modes) cannot be opened with EasyWMA and, since DSS is proprietary, there may not be any inexpensive converter to an equally compact format. The DSS files can be converted to AIF using Olympus's own software, but the resulting file is unwieldly at 10X the original file size.
The best solution would be for Express Scribe to upgrade their format support to be compatible with this very popular digital voice recorder. I note that Express Scribe is SUPPOSED TO load both the WMA and the DSS files, but does not load either (from this machine). My distributor tells me that the DS-2 is probably the most popular voice recorder currently selling in AU. So one hopes NCH will perform this compatibility upgrade soon.