How to Connect an Audio Interface to a Computer
To connect an audio interface to a computer, plug it into a USB port with the cable in the box, install the maker's driver or control app (needed on a Windows PC, usually optional on a Mac), then select the interface as the input and output device in your DAW. Set the buffer to 128 samples for recording.
Steps on a Mac or PC
- Plug in the USB cable. Small interfaces run on bus power. The Scarlett 2i2 4th Gen guide lists a 900 mA draw, plus a 5V DC input for computers whose ports can't supply it.
- Install the driver or control app. On Windows, Focusrite Control 2 installs the Scarlett driver. On macOS, no driver is needed.
- Set it as the system sound device. On a Mac, select it in Audio MIDI Setup and choose Use This Device for Sound Input and for Sound Output. On Windows, pick it in Sound settings.
- Pick it in your DAW. On Windows, set the driver type to ASIO and choose the interface's ASIO driver. On a Mac, choose the interface under Core Audio.
- Set the buffer size. Start at 128 samples while recording.
- Plug in a mic or guitar and watch the meter. Gain and monitoring are covered in how to use an audio interface.
Why a PC needs the ASIO driver
Windows 10 release 1703 and later ship a built in USB Audio 2.0 driver, so most interfaces play sound when plugged in. Ableton notes that low buffer sizes are hard to reach with the default MME/DirectX driver, so install your interface's ASIO driver.
Universal Audio says its Volt works without a driver on Windows but gets lower latency with its ASIO driver. ASIO4ALL is a last resort, for interfaces with no ASIO driver of their own.
What buffer size to use
Native Instruments recommends 128 samples for recording and 1024 for mixing with many plugins. Smaller buffers cut delay but tax the CPU, so step up if you hear crackles.
| Buffer (samples) | At 44.1 kHz | At 48 kHz | Use |
|---|---|---|---|
| 64 | 1.5 ms | 1.3 ms | Recording, fast computer |
| 128 | 2.9 ms | 2.7 ms | Recording |
| 256 | 5.8 ms | 5.3 ms | Recording or light mixing |
| 512 | 11.6 ms | 10.7 ms | Mixing |
| 1024 | 23.2 ms | 21.3 ms | Mixing with many plugins |
The table shows one buffer's length. Lynx Studio explains that round trip delay adds the input and output buffers, system buffers, and the converters' own delay.
Still hearing a lag? Use the interface's direct monitor. Still choosing hardware? See the best audio interfaces for home recording.
Related questions
Do I need a driver for my audio interface on a PC?
Windows 10 (release 1703) and later include a USB Audio 2.0 driver, so most interfaces make sound right away. Install the maker's ASIO driver anyway for low latency in your DAW.
Do I need a driver on a Mac?
Usually not. Focusrite says a Scarlett needs no driver on macOS, only its Focusrite Control 2 app for settings.
What buffer size should I use?
Use 128 samples while recording and raise it to 1024 for mixing with many plugins. If you hear crackles, go up one step.
More answers: Home recording FAQ