Tuning your own instrument in a noisy environment is always a problem, and I think some of the expensive tuners are smarter about picking your instrument out of the mass of people tuning up.

Even in a noisy environment, the cable picks up the sound of the instrument w/o interference.

but I would have expected the Korg to tune in a somewhat noisy environment like Guitar Toolkit.

However, without the cable you might not get 100% accuracy, also if your outside or in a noisy environment, you won't be able to use this feature due to the product picking up noises from around you

but it has trouble(slow) tuning the E

but it has trouble(slow) tuning the E