Yes, 10% - 15% is typical. But very frequently in the category you are in, it can be worth not doing high end interconnects. Save money and apply to component upgrades. I suspect if you doubled the investment in your integrated amplifier or source components the difference in interconnects and cables will become much more profound. Systems are like scientific instruments… the better they get the more sensitive they are. No reason to waste money on stuff that does not increase your musical experience.
When starting out there a lot of ambiguity in what you sense. As your experience and quality of your gear improves the ancillary stuff will make larger and larger differences. Consider yourself lucky for now. Enjoy your system and then if you choose to upgrade your system… recheck to see how much cables etc make a difference.