Connect an audio interface to your Mac, via either a FireWire or USB cable, depending on the make and model of the interface. Audio interfaces perform a similar function to a studio mixer. They provide instrument sockets and signal amplification for your instrument, before sending the audio signal to the Mac. The FireWire and USB sockets are located on the side of Macbook and Macbook Pro machines and on the front of desktop machines. Audio interfaces are typically bus-powered, meaning they draw their power from the Mac and need no external power supply.
Connect a 1/4-inch jack to your acoustic guitar output.
Connect the other end to the “Instrument Input” on the audio interface.
Launch your preferred digital audio workstation, such as Logic or Pro Tools.
Create an audio channel. Exact methods vary according to which program you use, but you typically click “File” and select “Audio.” In Logic, you can open an audio channel by clicking the “+” icon and selecting “Audio.” When you select “Audio,” the digital audio workstation automatically assigns the connected audio interface as the primary input device.
Play the guitar and monitor the volume units meter on screen. If it flashes red, this is a warning that signal is too high and it will distort on recording. Reduce the “Gain” dial on the audio interface. Set it as high as you can without making the warning light flash, this way you get a nice loud recording.