i actually found that they sounded bit more shrill
Check the settings on the backside of the HS7 speakers, what are "Room Control" and "High Trim" set to?
Also, a few things to keep in mind:
1. Studio monitors will always sound very different to a guitar cab in the room, first and foremost due to the much smaller woofer. A 6.5" woofer will never come close to a 12" woofer. Second, the typical sound pressure level you're playing through studio monitors is much lower than playing through a guitar cab. This changes the perception even further.
Headphones "feel" better because:
a. You likely listen louder on headphones
b. Headphones have a better bass response compared to the 6.5" loaded HS7 monitors
c. Bad room acoustics are out of the equation.
2. The room and the position of the studio monitors makes quite a big difference, as mentioned by others. Never underestimate the importance of at least some sound treatment!
3. Listen to your favourite (recorded) music a lot through these studio monitors, listen at the same perceived volume you want to play your guitar. Optimize the settings on the HS7 speakers. Get used to the sound of the monitors and start listening closely how the guitars (and other instruments) sound in the mix of your favourite bands' recordings. You might like the sound of your favourite recorded music/bands but still wish to "overpower" your own guitar playing. That's a common problem with people that are used to play loud and through guitar cabs. Take your time, listen to a lot of music, try to make your guitar "blend in" nicely (not blast over the entire backing track).
4. Always keep in mind that the Kemper Profiler delivers whatever you want ... and more. If you haven't messed up the settings of the Profiler, it will deliver. It just depends on how you want to translate the sound to the place you're in and your ears. The question is if these relatively small studio monitors will ever make you happy. If volume isn't an issue for you, if you can play loud, consider getting something like the Yamaha DXR10.