AmpKit works with virtually all guitar interfaces available for iOS devices, including digital interfaces that connect to the 30-pin or Lightning ports on your iPhone, iPad, or iPod touch, and analog interfaces that connect through the headset port.
On newer iOS devices, we recommend using a good-quality digital guitar interface, because a good digital interface greatly reduces noise and virtually eliminates crosstalk, both key characteristics especially when using AmpKit's realistically-modeled high-gain amps. Among digital interfaces, Peavey AmpKit LiNK HD provides a particularly rich set of features at a competitive price.
If you use an older iOS device, such as an iPhone 3GS or iPod touch (3rd generation), digital interfaces probably aren't an option, so an analog guitar interface will be your best solution. As with digital interfaces, some analog interfaces work better than others, especially with AmpKit's high-gain amps like the Peavey 6505+. Feedback is all too likely if the interface has issues with crosstalk. Among analog interfaces, Peavey AmpKit LiNK has fewer issues with feedback since it includes active circuitry to reduce crosstalk.