Not that this will come as a shock, but perhaps AudioKit is not the most accurate FFT when it comes to low end. Here's the Waves frequency analyzer screenshot from the file I took yesterday, without mastering HPF on - not much different. It certainly feels lower, and sounds great, but not sure I'm getting that low (at all). May try again today with my Zoom H2 just for fun.
Has anyone found a RTA/FFT that seems more accurate given the built-in mic? This is just for fun, so I'm not using it for mission-critical gigs.