Roger played a vintage '59 Les Paul throughout his career with Supertramp. That guitar and a Boss CE-1 is more important for that sound than the actual amp. He's playing with moderate gain and lots of Chorus. I know he played the CE-1 on the tour before that album so I'd assume he used that one still. It was kind of his trademark.
As far as the amp goes, although I was already around when the album came out, I don't remember having read anything about Rogers amps in the magazines back then. It was common knowledge what his guitar was and that he loved his Roland/Boss Chorus (and a Wah), but I don't remember anything about his amp(s).
If you want to replicate that sound, you need a Les Paul with low output PAF-type pickups and then try the "Vintage Chorus" on the kemper going in a profile with moderate gain (something like a Deluxe could work).
Yep. The chorus is a powerful effect. It is one of my favs for clean and dirty sounds. You can use lots of chorus for chords and then just a little for lead work. Maybe that's why almost everyone has more than one chorus pedal.
I have an SD '59 in a strat which is pretty close to that PAF sound. Using 10's strings is best.
I found the question from the OP so interesting that I did some more research. Though I didn't find any old Magazin Interview I did however went through some live clips on youtube. There is a full concert from the '83 tour - following the album in question - available on Youtube. I even remember having seen it on TV back then. It was broadcasted by one of the two biggest TV-stations in Germany back then and I remember me and my bandmates (we were teenagers at that time) talking about that concert the next day in school 
Anyway there is not much footage of the backline, but in one camera view you can see a Mesa Boogie MK-series amp. It's impossible to tell which one (in '83 it could have been a MK I or a MK II). It is also not visible if it is Roger's amp or belongs to Scott Page or Fred Mandel who joined the band for that tour.
But it might be a hint. A Boogie MK II was widely used in those times (rather than a MK I). So you might look for a moderate gain MK-II profile (Top Jimi or Ampfactory come to my mind) and use the Vintage Chorus as I've already suggested in my last post. That should get you there when paired with a Les Paul with PAF-type pickups. The Vintage Chorus in the Kemper does a pretty good CE-1, there is even a "CE-1" labeld preset in the recent factory content. A CE-1 has a smooth but throaty sound and is easily recognizable. It's known Roger loved that pedal - as did many guitarists back in the day.
It also sounds really wet. Crank up the reverb.
It also sounds really wet. Crank up the reverb.
Yes very moist :).
Garrincha - some great research there! Nice one.
I love supertramp....
Please Let us know When you found the perfect rig
