Line Out Vs Line In: What's The Difference? (Explained!) - Vita Audio

Line Out Vs Line In: What’s The Difference? (Explained!)

When creating music or producing audio, you’ll often come across the terms line out and line in. These outputs and inputs are found in lots of different professional audio devices such as amps, mixers, and audio interfaces.

Understanding the difference between a line out and a line in is incredibly important as it’ll help you to avoid many of the common mistakes that musicians tend to make when connecting audio devices together. 

Line Out Vs Line In: What's The Difference? (Explained!)

With this in mind, our guide will take a detailed look at some of the key differences between line out and line in,

Including everything you need to know about line-level signals, as well as answers to some of the frequently asked questions. 

What Exactly Is Line Out? 

The musical term “line out” refers to an audio connection port that allows you to transfer a line-level audio signal to another device.

These line-level signals are usually strong enough to be transmitted without any notable drops in connection.

Line out, also known as “audio out” or a “sound out”, is often found on keyboards, guitars, synthesizers, mixers, bass amps, audio interfaces, and many more musical devices. 

It essentially allows you to transmit audio signals from any one of these devices to another. For example, some musicians might want to line out from their guitar amp and send the audio to a mixer. 

Similarly, you can also transmit an audio signal from a mixer’s AUX output into a device such as a keyboard amp.

One important thing to keep in mind is the fact that line out doesn’t have a built-in amplifier. We’ll explain the relevance of this later in the guide.

What Exactly Is Line In? 

A line in is essentially the opposite of line out, as it refers to an audio input port that allows an audio device to receive line-level audio signals from another, separate device. 

Line in is found on lots of different audio devices, including mixers, amps, integrated amps, audio interfaces, and even on certain keyboard workstations. 

As mentioned earlier, line out sends the line-level audio signal from one device, while the line in port of another device can then receive this same signal and process it. 

For example, if you had your guitar plugged into an amplifier and then connected it to your mixer or recorder.

You could simply plug your headphones or speakers straight into the line in, and then you’d be able to listen back to what you just recorded.

In the vast majority of audio devices, the line in ports can be found at the top, side, or back. Just keep in mind that they’re typically labeled as either “line in”, “sound in”, “audio in”, or simply “input”. 

Differences Between The Two

Differences Between The Two

There are lots of notable differences between the two, mainly due to the fact that line in and line out ports are designed to work in the exact opposite fashion for every audio device.

We’ll now look to explain some of these technical differences in greater detail. 

Direction Of Signal 

Perhaps the biggest difference between the two audio ports is the direction of the signal – the path in which the signal travels.

A line out port is tasked with transmitting an audio signal out of a device, whereas a line in port is responsible for bringing a signal into an audio device. 

In simple terms, line input is designed to serve as the load component of the audio signal, while on the other hand, line output serves as the source of the signal.


This next difference might seem a little technical and isn’t necessarily the most useful for how you use the two ports, but it’s still worth explaining in a little extra detail. 

Impedance is a term used to describe the opposition to the current flow of an electrical component. As a general rule, most line out connections provide an output impedance ranging from 100 ohms to 600 ohms. 

In contrast, line in connections and line inputs typically have a higher impedance reaching up to 10,000 ohms or more.

This incredibly high impedance enables them to easily accept the voltage levels in the range provided by line outputs (100-600 ohms). 

Using Speakers

If you own speakers that are either active or powered speakers, you can safely connect them to line out.

This is because active speakers come equipped with a built-in amp that can amplify the line-level audio from the line out so it can be played at a good volume and sound quality through the speakers. 

However, if you have passive speakers, you should avoid connecting them to both line out and line in. This is mainly due to the fact that passive speakers require external power amps to drive them. 

So, if you’re utilizing passive speakers, you’ll want to connect the audio device’s line out to the line in of a power amp.

The amp converts the line-level signal from the line out to speaker-level. Following this, you can then connect the speaker to the power amp’s “speaker out”.

Speakers are connected to speaker ports or speaker outs in professional audio equipment.

Speaker outs are ports that are intended to send speaker-level signals capable of driving speakers. Line-level signals are insufficient to power speakers.

Is Line-Level Signal Balanced? 

Both line out and line in ports deal with audio signals at line level.

These line-level signals refer to those that are sent between audio components such as mixers, audio amplifiers, televisions, and DVD players. It is the standard signal level for analog audio transmission between devices.

Technically speaking, line-level signals can be either balanced or unbalanced, with the type of cable that’s used for transmitting or carrying the signal often the determining factor. 

Line-level signals are typically unbalanced when carried by most 1/4′′ and RCA cables. Line-level audio signals carried by 14 TRS connectors, on the other hand, tend to be balanced signals. 

When it comes to noise and interference, balanced signals are generally less susceptible.

Whether an audio signal is balanced or unbalanced is mainly dependent on the audio connector and cable – not the port in which the connector is inserted. 

Balanced cables usually come with three wires inside the plastic casing – two of which serve as signal wires and the third one acting as a ground wire.

It’s interesting to note that these two signal wires transmit exactly the same copies of the signal, but in opposite polarities. 

In contrast, unbalanced audio cables only have two wires inside the plastic outer casing. One of these wires is the signal wire, while the other serves as a ground wire.

As touched upon above, unbalanced cables are more susceptible to noise and interference than balanced cables. 

Frequently Asked Questions

What Is Meant By Line In Line Out? 

There’s no audio port that is labeled as, or can function as both a line in and line out. This is because, as discussed earlier, the role of line inputs is unique and varies significantly from the design of a line output. 

Do Headphones Go In Line Out Or Line In? 

You might ask yourself why they’re different colors. This essentially means that one goes in line out and the other goes in line in. 

To make things easier, imagine you’ve got your guitar plugged into the red jack, you’d then plug your headphones or speakers into the green jack.

If you don’t know which one to use, you should probably stick with the green one because you won’t get any feedback when using the wrong one.

Why Does My Mixer Have Both Line Outs And Line Ins?

Some mixers will come with both a line out and a line in. These are called phantom power connectors. Phantom power is essentially a short circuit so you don’t need to worry about getting too much current going through your equipment.

If you only have one of these connectors, you can always buy another one. However, it’s worth noting that you may not find many places where you can purchase them separately.

Do Microphones Go In Line Out Or Line In? 

Ideally, microphones shouldn’t be connected to line-level outputs.

This is because microphones generate microphone-level signals, so when you connect a microphone to a line-level input, you’ll produce very little sound. 

Microphone-level signals are also relatively weak compared to other line-level signals, therefore they can’t be effectively transmitted through line inputs. 

Instead, they need to be connected to a mic input, also known as a “mic in” due to the fact they have a preamp built into them. This preamp works by receiving the weak microphone signal and then boosting it into a line-level signal. 

If, for example, you need to connect your microphone to an audio device that only has line-level input, you’ll need to first connect the microphone to a dedicated mixer or preamp to amplify the output signals. 

Can Line Outs Be Used For Anything Else?

Yes, there are lots of different uses for a line out besides recording audio. You can use them to send signals to lights, alarms, and much more. 

For example, you could hook up a light switch to a line out and control it remotely. Similarly, you could connect a motion sensor to a line out and turn on your security system when someone walks past.

What Are The Different Types Of Line Outs?

There are three types of line outs, with each one having its own purpose. 

XLR Main Output – these are used primarily for sending audio to external effects processors, monitors, etc. It also works well with mixing consoles that have an XLR input.

RCA Main Output – this type of line output is similar to the first one but it doesn’t require an adapter. Instead, you just plug the main outputs from your mixer into the inputs on your amplifier.

Instrument Inputs – instruments like guitars and keyboards often have their own dedicated line outs. This allows you to bypass all the effects pedals and send the sound straight to your amp.

Is line Out The Same As Speaker Out?

No, they aren’t the same thing. Speaker out refers to sending audio from your mixer or recorder to your speakers. This is done by putting a “speaker” output on your mixer or recorder.

On the other hand, line out refers to sending audio to an external device like headphones or speakers. It doesn’t matter whether that device has built-in speakers or not.

The Bottom Line

To conclude, understanding the difference between a line out and line in is essential when it comes to connecting audio devices together.

So, if you’re an aspiring musician and want to use lots of different instruments and audio devices effectively, the information in this guide is a great place to start!

If you enjoyed this article, you might enjoy our post on ‘Klipsch R-12SW Vs R-120SW‘.

Jacob Stable
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