I use a Steinberg MR816X which sounds amazing. The internet loves these things too.....seriously google them, and be pleasantly surprised
There is also a USB version if Firewire aint available.
But to be absolutely sure that you are getting the purest signal from your Kemper (if going direct and for FRFR) you have to go in to your interface via SPDIF. Digital 1s and 0s, and hence no signal loss with conversion, interference, etc etc...
Also the best thing about it, is that digital transcends price tags....a digital IO in a €100 soundcard will sound the exact same as the digital IO on a €3000 interface. Just digital 1s and 0s after all......
But if you want to use the mic pre amps and converters for your monitors, then the differences can be heard...
BTW, Focusrite are grand devices (mostly), I have frequent access / use a LS56 very often and its a lovely piece of kit. Bit big for my home rack though for my needs (2U rack space)