The Xitona Guitar Tuner application was designed to be an simple interactive software, which determining exactly pitch of your guitar strings, by using microphone and sound card. It also can work without microphone. As a last resort you can plur headsets into microphone input. It works with most of sound cards.

If you think you can tune your guitar exactly using only reference tones, you’re poorly wrong. Theoretically, when you are using reference tones and the frequencies are roughly the same, a great resonance is produced.

In this case reference tone become a source of forced oscillation, which cause strings oscillation on the same frequency. And it sounds like guitar is tuned. But actually own string frequency can greatly differ from reference tone. That’s why preferably to use passive system which only listen and does not provide any sound oscillations.