I'm afraid we have been very sloppy about versions with this design, which goes back to the earliest days of Electronic Tonalities before it became Bottlehead. So here's what I recall - anybody has more or different information, let me know and I'll edit this post.
***** Original S.E.X. was a pair of parallel SE monoblocks, introduced in 1996.
A revised manual labelled "Rev 1.1" is dated 1997, though most of teh changes were introduced earlier with "pink slip" addenda to the manual.
A second revision of the manual is labelled "Rev 2.0" and also dated 1997; the changes had happened by May of that year.
In early 1999 it was replaced with the ParaSEX, incorporating a parafeed output that had been an upgrade kit.
In 2000 the Paramour 2A3 monoblock came out and replaced the ParaSEX.
***** Stereo SEX appeared in 2004. At the time we did not give it a version or revision label
(Since then it has been referred to informally as version 1, 1.0, 2, or 2.0, depending mostly on whether the speaker remembered the Original S.E.X. amp.)
Version 2.1 appeared in 2012, incorporating the new output iron among other changes. It is labelled V2.1 on the manual title page.
