Monitoring Kemper

Hey all! Im a brand new KPA user, and my question is regarding monitoring the KPA. I just got mine yesterday, and only had time to load a few profiles in and eq it a bit before going and playing a gig. I really liked the tone i had in my ears and in the house, but when i plugged everything back in to my computer it does not sound the same. It sounds like theres a bit of tone loss. I am running the KPA into a Line 6 GX interface, and then into my computer with garage band using a line input option. I am plugging my dual driver IEM's into my mac's headphone jack to monitor it. Am i doing this correctly? Or is there a better way to do this?

^{I havent tried the headphone jack yet, I will pick up a headphone adaptor and try that tomorrow!}