I think it can get even worse. I'll spend hours delightedly playing with a couple of rigs that have "my sound", then return to the same rig, same guitar, different day and wonder what the hell happened to make it sound so lame. Drives me crazy but I'm pretty sure the Kemper isn't the problem...maybe some Fletcher Munson corollary, I don't know, but I imagine it's a human problem.
Also, to your question, and although I have no sane reason for doing so, I bought an Atomic CLR Neo II wedge. Kinda pricey, but in combination with the Kemper, literally the most fun I've ever had. Really brought things to life in a way my headphones couldn't. No affiliation, just sayin'. My $0.02, hope you find your sound!