The first question is whether you will have enough gain. I think you probably will, but you can substitute your SEX amp for the FP/Paramour combination to be sure - they have very nearly the same sensitivity. Probably the Seduction is your lowest-output source; put on a relatively quiet record and see if you can get enough gain. If so, then Stereomour will have enough gain without any preamp.
Some people like a preamp anyhow; most often I hear comments like "better dynamics" or "punchier". It has not struck me that way, but we all have different ears and I do not doubt that others are hearing what they say they are hearing. The extra two stages in Foreplay do add some "flavor". Usually I prefer my electronics as unflavored as possible. It may depend on what music you like.
Not much help, I know!