Every audio interface that is made nowadays, especially the budget options, has a preamp built-in, and it makes sense. Having an all-in-one interface where you can plug in a microphone or any instrument and start recording is great, especially for beginners, and saves you a lot on gear.
But what if you already own a preamp? Is there a way to bypass the preamp on your audio interface?
The best way to bypass an audio interface’s preamp is to use the line-level inputs on your audio interface instead of the combo jack inputs. The combo jack inputs usually have the preamp built into them. Alternatively, you can use the ADAT input on your interface to receive digital audio input from external devices. If you have no line inputs or ADAT input on your audio interface, the last option is to use the combo jack input and turn the gain down.
The ability to have a toggle switch on an audio interface that allows us to switch on or off the preamps is something we have all wished for. We wish it was that simple. However, manufacturers seem not to bother about this feature. That’s because most budget audio interfaces are made for beginner music producers who are not very keen on recording quality, unlike professionals.
There is no denying the fact that some standalone preamps sound incredible. If you have ever owned a preamp, then you probably know for sure that they usually sound better than the preamps in budget audio interfaces.
That is not to say the preamps on these budget audio interfaces like the Focusrite Scarlett 2i2 or the Behringer UMC22 are bad. They sound very decent, clean, and transparent for the price, and it gets the job done for most music producers. Don’t get it wrong, hit songs have been made with budget audio interfaces.
However, there is a color, a specific tone, and a certain level of sweetness that some standalone preamps give to your recordings. And most audio interface preamps can’t emulate that, unless it’s an expensive interface, of course, which is why experienced music producers and recording engineers prefer using external preamps over built-in preamps on audio interfaces.
So, if you want to use an external preamp, it’s a good idea to bypass your audio interface’s preamp. That’s because running the output of your standalone preamp through the preamp on your audio interface will color the sound in a way you might not like. It can also cause noise or distortion if the gain on each preamp is not set properly.
So how do you bypass an audio interface’s preamp?
Ways to Bypass an Audio Interface’s Preamp
1. Use the Line Inputs on the Audio Interface
If you own an audio interface with Line Inputs, then you are in luck.
The Line Inputs on an audio interface are made to receive pre-amplified signals, also known as a line-level signal. For this reason, line inputs on audio interfaces don’t have preamps built into them. The signal received by line inputs is hot enough to be processed by the Analog-Digital converters in your audio interface, straight into your DAW.
Connect the Line-Out on your standalone preamp or mixer to the Line-Input on your Audio interface to bypass the preamp on your audio interface.
Line inputs on audio interfaces mostly 1/4 inch line-ins. If the line-out on your standalone preamp is a TRS port, then simply plug one end of a TRS cable into the Line-Out TRS Port on your preamp, and then plug the other jack into the Line Input on your audio interface.
However, most Line-outs on preamps are XLR outputs. If you own a preamp with, you will need an adapter or a cable that will go from an XLR female to a TRS male jack connector. This cable on Amazon will get the job done.
Something to note is, Line Input on audio interfaces are usually at unity gain. It neither reduces nor boosts the dB level of the signal. This means you need to set the gain on your preamp at the right level to get a good line-level signal.
If your audio interface does not have line inputs, I’ve compiled a huge list of audio interfaces without preamps. I highly recommend you check it out because there is an option for every budget.
2. Use the Audio Interface’s ADAT Input
Using the digital audio input or ADAT input on your audio interface is an excellent way to bypass the audio interface’s preamp.
If your external preamp or mixer and audio interface has ADAT ports, I highly recommend you go with this option.
ADAT allows you to transmit up to eight audio signals or channels from one device to the other. You won’t find ADAT in a one or two-channel preamp, but they are very common in 8-channel preamps such as Behringer’s ADA8200 Microphone Preamp (on Amazon) and a premium option like the Audient ASP800 Mic Preamps (also on Amazon)
Connect the preamp or mixer’s ADAT output to the audio interface’s ADAT input with an Optical/Lightpipe ADAT cable to bypass the interface’s preamp.
Audio signals from your external preamp or mixer get transmitted to your audio interface digitally through the Optical ADAT cable at ultra-low latency. Since the signal from your external preamp is already a digital signal, it won’t be converted by your audio interface’s A/D converter. It will simply be reformatted and sent to your DAW.
3. Use the Combo Jack Input and Turn Down the Gain
This is the last option you’ve got if the first two ways don’t work for you.
The combo jack inputs on your audio interface will have a preamp built into them. These inputs are uniquely designed to accept Mic, Instrument, and Line Level signals.
However, we don’t want to amplify the audio signal coming from our external preamp or mixer with the built-in preamp on our interface. That’s because the signal will be at line-level and is already at a very good dB level.
Turn the gain level on your audio interface to zero. Connect the Line-out of your preamp to the combo jack input on your audio interface with an XLR or TRS/TS cable.
This is not the best option out of the three, and here is why.
When you connect the external preamp’s output to the audio interface’s combo jack input, the signal goes through the variable gain section of the interface’s preamp circuit. In essence, the audio interface’s preamp is not bypassed.
However, turning down the audio interface gain reduces the effect the interface’s preamp has on the signal. Some of the budget audio interfaces have a “transparent” preamp. This means you will not notice any significant changes to your signal when they are sent through the preamp.
Why most budget audio interfaces have a preamp
Budget audio interfaces are made with the beginner in mind. What do I mean by this?
Most beginners don’t know the technical aspects of recording. Most beginners don’t know what a preamp is, the difference between Mic, Line, and Instrument level input; their ears are not trained enough to know the tonal difference between various preamps, and so on.
To make it as simple as possible for starters, manufacturers decided to make an all-in-one device that does it all. That was why the combo jack input was designed in particular.
You can simply plug in a microphone, which requires a preamp, a guitar or bass, which also requires a preamp, or a keyboard or synthesizer, which doesn’t require a preamp, into a combo jack input and start recording. And you don’t even need to know the difference between the signals. You simply plug it in and record. This is why most audio interfaces have a built-in.
Only intermediate and professional music producers and recording engineers care enough about the difference a built-in preamp will make to their audio signal.
Are there audio interfaces without preamp?
Yes, there are audio interfaces without preamps. Typically, these audio interfaces have only line inputs or DB25 (D-Sub) connectors, and there will be no combo jack inputs on them.
However, there are a lot of audio interfaces that have some inputs with a built-in preamp, and some without a preamp. In my opinion, those are the best options because they have preamps on some inputs, just in case you need it, and you still have line inputs if you don’t need the preamp.
I’ve compiled a list of audio interfaces without preamps. Personally, I’ve used some of these interfaces before, and others were recommended by expert recording engineers. I recommend you check it out.
To bypass the preamp on your audio interface, use the line inputs or ADAT inputs. Audio signals recorded through the line inputs don’t pass through the preamp circuit of your audio interface. Similarly, audio signals received by ADAT input on your audio interface gets recorded into your DAW without any preamplification.
If there are no line inputs or ADAT input on your audio interface, then use the combo jack inputs and turn the gain level to zero. This will not bypass the audio interface’s preamp but reduce how much change it does to your audio signal.