To connect an electric guitar to a Mac, you will generally need the following:

1. A1/4-inch standard guitar cable (also known as a TS cable or instrument cable) to connect your guitar to an audio interface. This is the typical cable you'd use to connect your guitar to an amplifier.

2. audio interface that is compatible with Mac. The audio interface will convert the analog signal from the guitar into a digital signal that the Mac can process. It often connects to the Mac via USB, Thunderbolt, or FireWire depending on the model and age of both your Mac and the audio interface.

3. A compatible connection cable (USB, Thunderbolt, or FireWire) to connect the audio interface to your Mac. The type of cable required will depend on the ports on your Mac and the audio interface.

4. Optional: Audio software (often referred to as a Digital Audio Workstation, or DAW) to record or the guitar signal. Macs come with GarageBand, which is capable of recording guitar and includes a variety of built-in effects and amp simulations.

When purchasing an audio interface, make sure to check the type of connection it uses and verify that your Mac has the corresponding port. If not, you may need an adapter to connect the interface to your Mac. If your Mac only has USB-C ports (common on newer MacBooks), your audio interface uses a USB-A connector, you'll need USB-C to USB-A adapter.

When selecting a good audio interface to connect your electric guitar to your Mac, there are several reputable brands and models that cater to a range of needs and budgets. Some popular options include:

1. Focusrite Scarlett Series: The Scarlett 2i2 or Scarlett Solo are popular choices for beginners and semi-professional musicians. They provide excellent preamps, are very user-friendly, and offer great value for the price.

2. Universal Audio Apollo Twin: This is a higher-end option that provides top-quality preamps, excellent converters, and built-in UAD-powered plugins to emulate classic analog gear. It is suitable for professional recordings.

3. PreSonus AudioBox USB 96: An affordable option for beginners that offers solid build quality and performance to get you started with recording your guitar.

4. Steinberg UR22C: A robust interface with great audio quality,, and compatibility with USB 3.0 and USB-C connectivity.

5. IK Multimedia iRig 2: This is a portable and straightforward interface designed specifically hooking up guitars to mobile devices or computers, perfect for practicing or recording on the go.

6. MOTU M2 M4: These interfaces have excellent metering, low latency, and are well-regarded for their sound quality and durability.

7. Behringer U-Phoria UMC204: A budget-friendly interface with MIDAS preamps and a lot of features for its price point.

When choosing the right audio interface for your needs, consider the following:

• The quality of the preamps, as they greatly affect the sound of your guitar recordings.
• The number of inputs and outputs required. If you only need to record your guitar, a single-input interface like the Scarlett Solo or iRig HD 2 might be sufficient.
• Latency performance, which crucial for real-time playing and monitoring.
• Connectivity options (USB, Thunderbolt, etc.) that match Mac's ports, or for which you can get an adapter- Compatibility with your Mac's operating system.
• Your budget, as interfaces can range from under $100 to over $1000.

Remember that modern audio interfaces should be compatible with Macs, but always check for the latest drivers or software updates from the manufacturer to ensure compatibility, especially if you are using the latest version of macOS.

The Focusrite Scarlett series is a very popular line of audio interfaces among musicians and producers. Each of the models you have mentioned caters to slightly different needs. Here are the key differences between them:

1. Focusrite Scarlett Solo USB Audio Interface (Gen 3):

   • This is the smallest and most straightforward audio interface in the lineup.
   • It provides one microphone preamp (XLR input) with phantom power for condenser mics and one instrument input (1/4" input) for connecting a guitar or bass directly.
   • It has two balanced outputs (1/4" TRS) for monitors.
   • It's an excellent choice for solo artists or musicians who only need to record one instrument or voice at a time.

2. Focusrite Scarlett 2i2 USB Audio Interface (Gen 3):

   • This interface is a step up from the Solo, offering two microphone preamps (XLR/TRS combo inputs) with phantom power, meaning you can plug in two microphones or one microphone and one instrument, or two instruments simultaneously.
   • Like the Solo, it has two balanced outputs for monitors.
   • It's ideal for artists who may want to record a microphone and an instrument at the same time or for those who may want to record stereo instruments.

3. Focusrite Scarlett 2i2 Studio Pack (Gen 3):

   • The Studio Pack includes the Scarlett 2i2 USB Audio Interface mentioned above.
   • Additionally, it comes with bundled accessories aimed at providing everything you need for a home studio setup. This typically includes a condenser microphone, a pair of headphones, and a microphone cable.
   • This package is geared towards musicians or producers who are starting from scratch and need the basic gear for recording.

All three of these models (Gen 3) would include Focusrite's Air feature, which can add a brighter, more open sound to your recordings when enabled. They come with a support for high-quality 24-bit/192kHz audio and connect to your Mac via USB.

Remember, the best choice depends on your specific needs, such as the number of simultaneous inputs you require, and whether you need additional equipment like a microphone and headphones to start recording.