Use a Digitech GNX4 as an Audio Interface in iOS

In this post, we’ll learn how to use a Digitech GNX4 as an audio interface in iOS. The GNX4 will work as an interface in iOS and iPadOS with just about any audio application using the official Apple USB adapter and a USB cable. The best part of the GNX4 being supported is that there is no need for drivers. You read that correctly. The GNX4 is a compliant device and is supported with plug and play by your iOS devices. Let’s get started!

10 June 2020 – Written by Michael R. Myers #mykmyrs

Skill Level: Beginner

Recently on the Facebook Digitech GNX4 group, a member asked how he could use his GNX4 as an audio interface for recording with an iOS device. In all the time I’ve used a 2011 iMac with my GNX4, which supports the GNX4 without any drivers, I hadn’t considered trying to hook my GNX4 directly into an iOS device as an interface to record. His question prompted me to give it a try on my iPad Air 2 and I can tell you that the GNX4 is supported as an audio interface in iOS.

Before you continue, you must have an official adapter from Apple to use as the connection interface between the GNX4 and a lightning iOS device. This adapter, which costs around $40 USD currently, provides a USB port and an additional lighting port. The additional lightning port allows for powering the iOS device while a USB device is also connected. Do yourself a favor and buy the official adapter because the cheap ones on Amazon and EBay often are not recognized by the iOS device, and if they are, can fail to transmit audio.

Configure Your GNX4’s USB Output Source

You may need to make a configuration parameter change on your GNX4, depending on what you’re going to record in your iOS application. Are you intending to record the actual audio output from your GNX4 patch, meaning the guitar signal, amp, cabinet and all effects? Or are you intending to send a dry guitar signal to the iOS app and use virtual amps, cabinets and effects within the application? You need to make sure you have a clear understanding of “what” you would like to record, otherwise sending a full-effects signal from the GNX4 into iOS may end up being sent through iOS amps and effects.

To change your GNX4 USB audio settings, see my previous post here. For the steps that I list below, I wanted to send the dry guitar signal from the GNX4 to an iOS guitar application to make use of the app’s amp, cabinet and effects. To do the dry signal, I configured USB 1-2 to be “DRYGUITAR” on the GNX4’s configuration settings.

What You’ll Need to Get Started

  • Digitech GNX4 unit with a USB cable
  • Apple iPhone or iPad with Lightning connector and built-in headphone jack
  • Apple iOS version 13 (not tested on any other versions, but may work)
  • Official Apple Lightning to USB 3 Camera Adapter
  • headphones or stereo audio cable to plug into headphone jack
  • IOS guitar application, such as GarageBand – available free in the AppStore

Steps to Connect Your GNX4 to an iOS Device

  1. Connect your USB cable from your GNX4 into the lightning adapter’s USB port.
  2. Connect a lightning cable into the adapter for a constant power source.
  3. Connect the lightning adapter into the iOS device.
  4. Plug your headphones or stereo line out cable into the iOS device
  5. Power on your GNX4.
  6. Open your iOS guitar application. Set its input channel to 1 for the guitar input. Each application’s settings’ options will vary.
  7. Play your guitar and you should immediately see the input and output volume meters show signal. In addition, you should be able to hear the audio playing in the headphones.

Where To Go From Here

After I had signal in the iOS GarageBand application, I used a stereo headphone cable to send the headphone jack to my computer’s digital audio workstation (DAW) to record the iOS application’s audio output. This type of setup could be useful if you need an array of different amps for recording and you’d like to focus your work on the iOS device.


I didn’t expect the GNX4 to work as an audio interface to iOS devices due to its sheer age. I was pleasantly surprised that it worked with only a small parameter change for the USB audio and an adapter I already owned for my iOS devices. If you haven’t explored iOS applications for guitars, here’s an opportunity for you to give it a shot for a relatively small adapter expenditure. Good luck and make some great sounds!

If you would like to add to this content to help other folks, please contact me and let me know what you have in mind.