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jobsagoodun - the Text to Speech plugin uses Microsoft's Speech API (SAPI), which has been around since Win95. TTS is a generic name for a capability not a specific technology, so SAPI is MS's implementation of TTS.
A number of people have integrated Balabolka into calibre via the 'Open With' feature (built in or plugin). If you search the Calibre forum for 'Balabolka' you should find some posts. I use the built-in 'Open With' which I access via the View Specific format option (the kb shortcuts are assigned via Preferences->Keyboard):
Maybe you could integrate one or more of the TTS programs you mentioned in a similar way. Of course, you must attach the programs to formats they can 'read'
BR