The XLR adapter allows you to direct and choose which sound you want to capture. To use, you simply attach an XLR stick mic, plug in your headphones in the other receptor and plug in the device to the headphone jack on your iPhone/iPod. This device allows for professional quality sound to be recorded on the go. It is a lot cheaper than professional quality devices, such as a Marantz. The VeriCorder adapter is $60.00, but it is a great investment for professional-sounding audio. Some of our fellow journalism students have used devices such as these and ran the finished product on our NPR affiliate.
The KV Connection cable works under the exact same principle, only this kind of adapter is for a different kind of microphone. The great thing about the KV Connection cable, besides the price ($23.50), is that the adapter fits a 1/4 microphone, but you can buy another piece, for a small price, to put inside the adapter. This makes it multi-functional, for many different microphones.
(Note: For better sound, make sure to turn your iPhone on Airplane mode).