When working with amplifier simulators, such as AmpliTube, you will need to record a D.I. (Direct Inject) signal of your guitar. This is the clean, unaltered signal from your guitar's electronics, and will be uncolored by any other equipment prior to entering your audio interface. 

You will need the following equipment:

• A guitar with pickups and a quarter-inch jack connector
• A quarter-inch tip-sleeve (TS) cable (a typical guitar cable)
• An audio interface with a quarter-inch TS input
• A DAW of your choice
• Headphones or monitoring speakers
• A computer

You may also choose to use a D.I. box, which takes the unbalanced instrument signal from the TS cable and converts it to a balanced signal while potentially boosting or attenuating it, depending on the model of D.I. box. However, if your interface has an instrument input then this method isn't necessary because the interface will be designed to do this internally. 

Signal Chain

Now you will need to make sure your signal gets from your guitar into the computer. After connecting your interface to your computer, plug your guitar into one of the inputs—unless you have other equipment connected, it usually makes sense to use Input 1 on your interface. Most interfaces will have either combination or TS inputs on the front or back panel. Ensure that your interface has the Instrument option enabled on the input, as this tells the interface that we are sending an instrument level signal. This might be a physical switch, or could be changed through software that connects to your interface. Using the instrument input is important, as instrument signals have lower impedance than microphone signals, and are usually higher output, so this allows your interface to handle the signal correctly. 

Next, you will need to set the input gain for your guitar going into the interface. Most guitars do not need any adjustments, but some, especially those with lower output pickups, may need the gain adjusted.

1. With your guitar connected, play at what will be your highest volume, usually hard strums of the strings. 
2. Look at the visual monitor on your interface. Some may have a row of LEDs, others, like the Focusrite Scarlett 2i2, have a green ring around the gain control. Some interfaces may not have a physical indicator and may rely on software for input level meters.
3. As you play, adjust the gain control on the input that you have connected your guitar to. 
4. While playing your loudest, turn the gain control up until you see either the LEDs or other visual reference turn red. Then, back off until the indicators are back to green. 

In Your DAW

Now that your signal is set on the interface, you must ensure that your DAW is looking to the right place for the signal. The following section assumes you have some general knowledge about how your chosen DAW works. These steps are generalized and should apply to the vast majority of DAW programs. 

1. Set your input and output devices within your DAW to your audio interface. 
2. Create a new audio track.
3. Ensure that the Input for your track is set to the same input that you have physically connected your guitar to on your interface. 
4. Either record enable, or enable input monitoring on your audio track; you should now be able to see signal come in when you play on your guitar. 
5. Lastly, add whichever amplifier plug-ins you are using on the audio track.