“I own a midiman Audio Buddy, if I have the phantom power switch on, how will that affect the other mic input, as well as the high impedance guitar input?”
For the first half of your question we will defer to the numerous inSync articles written on the topic of Phantom Power. Here you will find information regarding (among many things) the relationship between Phantom Power and different style microphones. Turn your browser to www.sweetwater.com/insync and type in phantom power in the search engine and you’re off to the races.
Some devices have individual Phantom power selectors for each microphone input, but these days more and more devices have one phantom power switch for all mic inputs, as is the case for your Audio Buddy. This is partly to lower costs, but also because more and more devices these days can be plugged into a powered mic input like this without being damaged. As more and more products are built without individually selectable phantom power switches we’ll continue to see more devices that can be plugged in to them without harm.
The two areas where you still need to be extremely careful plugging into phantom powered XLR inputs is with old ribbon mics and line level gear. Many guitar preamps and other devices with XLR outputs are not built with phantom power in mind, and can be damaged by it.
As for the high impedance input, phantom power is applied to pins 2 and 3 on an XLR mic input and therefore shouldn’t show up on your high impedance guitar input at all. You shouldn’t have any problems.