Fantastic app
Absolutely fascinating. I just discovered the other day that when you sound two tones from a cord, say E5 and G5, the tuner picks up the beating tonic, C4! This is fascinating. The only suggestion for minor improvement I have is to enable arbitrary frequency range setting in the FFT spectrum.
DarkoMatovic about
insTuner - Chromatic Tuner with Tone Generator, v2.0