Hi Dupe,
I have just viewed the two Genos voice files "WhiterBars JS.T235.sar" and "ClassicBars JS.T235.sar" in the "Mixmaster" program:
In "WhiterBars JS" the insert effect type "V Distorion Classic Soft" is used, but "Stereo Amp Sim Clean" is used for "ClassicBars JS". This is probably similar with the SX700 versions of these voices. Probably this distortion effect is the reason that you have "noticed a distinctive distortion".
With these voices on the SX700 in "Mixer (Panel page) > Effect" or in "Voice Edit > Effect" you could see which effect is activated and change these settings if necessary or select another effect type.x
By the way, if you change the Effect settings of a Preset Voice (in Mixer or in Voice Edit), you can either save the edited Voice in "Voice Edit" as a User Voice or, alternatively, directly into a Registration (i.e. without creating a User Voice beforehand).
Best regards,
Chris