In some situations, it may be useful or become necessary to defeat a signal’s path to ground. For example, if your studio is plagued with ground loops, or noise issues, breaking a path to ground may solve the problem. Ground lift is a switch found on many pieces of audio equipment which disconnects audio signal ground from earth or chassis ground.
Using ground lift switches is considered to be far safer than the old “3-to-2 prong AC adapter” solution (which we heartily DON’T recommend, see TTOTD from February 24, 1997 for more on this topic). However, occasionally ground lift switching will not be as effective in resolving problems as the brute force AC adapter might be.