Octa,I'm glad you Are happy with the raidho's.I also agree about cables,I have never heard the"night and day" difference that you sometimes hear about,luckily my dealer lets me demo cables...I don't think I ever returned any thoughNo I haven't heard the SN2 with Raidho's (only the nap500). But Callas01's friend had the SN2 with Dyn C4 Sigs then upgraded to the Raidho D2's (nothing sounds bad in Callas01's girlfriends room ).
As far as a lot better? Maybe - I say that because some folks will hear Raidho Diamond series and be 'haunted' by the sound signature. Others will like them a lot but can't justify the cost. A few may not even like them. But if your taste is like mine you will be haunted by the sound.
IMO cables should be the final tweak. If your equipment changes the cables may degrade the sound (depends on the cables). In most cases a better cable will usually sound better but if the synergy (musical to detailed or visa versa) changes too much it could be a pretty big problem. IMO again a good middle of the road cable is hard to beat until you finalize a system. Even then the cables will only add a couple to few percents better (but all the percent does add up)