In this article, we’ll share 3 different ways to connect an audio interface to a headphone splitter or amplifier. We’ll cover why you might want to do this and explain why one of these methods doesn’t work as well as you might expect.
Quick Answer: The easiest and most effective way to connect an audio interface to a headphone splitter amplifier is to run a single balanced 1/4″ TRS cable from the interface’s headphone output to the input on the headphone splitter.
Why Connect A Headphone Amp / Splitter To An Audio Interface?
There are 3 different reasons people typically want to connect a headphone amp or headphone splitter to an audio interface.
- Split the headphone output multiple ways
If you’re working with other people, say when recording a podcast, they’ll need to monitor the signal from your audio interface too. Nobody gets a custom mix, but everyone can hear what’s going on. - More volume
Some audio interfaces don’t have a strong enough amp to power high-end headphones. A headphone amplifier addresses this by boosting the signal again, giving you more volume in your headphones.
- High-end preamp with other features
You want to use a high-end tube preamp that adds tonal coloration or other features that you like to have when using your favorite headphones.
Audio Interface & Headphone Splitter / Amp Equipment
We’re using the Focusrite Scarlett 2i2 audio interface and Mackie HM-4 headphone amplifier splitter in the accompanying video. However, these methods will work with other audio interfaces, including those listed below.
- Focusrite Scarlett 2i2 Interface: https://currentprice.io/scarlett_2i2
- Mackie HM-4 Amplifier Splitter: https://currentprice.io/4ch_splitter
- Solid State Logic SSL2+ Interface : https://currentprice.io/ssl2_plus
- Motu M2 Interface: https://currentprice.io/motu_m2
If you want to learn how to connect an audio mixer to a headphone amp splitter, check out the linked article.
Balanced vs. Unbalanced Cable
Before we get into how to connect an audio interface to a headphone splitter, we need to cover a little bit of theory surrounding balanced and unbalanced 1/4″ cable.
- Unbalanced cable
Unbalanced cable connectors have a tip and a sleeve, and they are also known as TS or instrument cables. An unbalanced cable is not suitable for a stereo signal, and it can only carry a mono signal over a distance of less than 15′. - Balanced cable
Balanced cable connectors have a tip, a ring, and a sleeve, so they are known as TRS or tip ring sleeve cables. Balanced cables can carry an unbalanced stereo signal 15′ or a balanced mono signal much further.
Balanced Mono Vs. Unbalanced Stereo
As we mentioned a moment ago, you can use a balanced cable in 2 different ways. Let’s take a closer look at each one.
- Unbalanced stereo signal
This is perfect for headphones requiring a stereo signal over a distance of up to 15′. - Balanced mono signal
A balanced mono signal consists of two versions of the same signal, one of which is phase inverted. These signals are used to cancel out noise from the cable, making it practical for connecting speakers over distances of up to 100′.
Method 1: Headphone Jack To Headphone Amp
Headphone output > Balanced TRS cable > Headphone amp input
Pros:
- Stereo signal
- Simple, single-cable setup
- Headroom on interface and headphone amp
- Headphone volume knob on the interface
Cons:
- Audio interface headphone preamp can introduce noise
It’s typical for the headphone preamp in an audio interface to get noisy at 60%-75% of its max volume. We recommend finding the point at which noise becomes noticeable, backing the volume off, and adding more volume at the headphone splitter/amp.
It’s worth noting, the noise in your headphones isn’t necessarily present in the actual recording, as it’s only being added by the headphone preamp.
Method 2: Left Line Output To Headphone Amp
Left line output > Balanced TRS cable > Headphone amp input
Pros:
- Simple, single-cable setup
Cons:
- No stereo signal; you only hear the left channel in one ear
- No physical volume knob
We don’t recommend using this method as you will only have audio in one ear. The left line output sends a balanced mono signal to the headphone splitter, but the headphone splitter is expecting a stereo signal and can’t unpack the balanced mono signal.
Method 3: Both Line Outputs To Headphone Amp
Line outputs > Dual 1/4″ TS to 1/4″ TRS cable > Headphone amp input
Pros
- Stereo signal
Cons
- Slightly more complicated setup
- No physical volume knob
This method eliminates the problem of only having audio in one ear as both channels are now being fed to the headphone amp splitter. The downside to working this way is that there is no volume control for these outputs on the interface; you need to make any adjustments using software.
Audio Interface & Headphone Splitter / Amp Pricing & Specs
- Focusrite Scarlett 2i2 Interface: https://currentprice.io/scarlett_2i2
- Mackie HM-4 Amplifier Splitter: https://currentprice.io/4ch_splitter
- Solid State Logic SSL2+: https://currentprice.io/ssl2_plus
- Motu M2: https://currentprice.io/motu_m2
- Shure SM7B Microphone: https://currentprice.io/shure_sm7b
- Cloudlifter CL1 Preamp: https://currentprice.io/cloudlifter
- 1/4″ Balanced TRS Cable: https://currentprice.io/trs_cable
- Dual 1/4″ TS to 1/4″ TRS Cable: https://currentprice.io/14_2ts_trs
- Beyerdynamic DT990 Pro Headphones: https://currentprice.io/beyer_dt_990
- XLR Cable: https://currentprice.io/xlr_cable
- TRS Cable: https://currentprice.io/trs_cable
- Mic Stand: https://currentprice.io/desk_stand
- Rode PSA1 Boom Arm: https://currentprice.io/boom_arm
How To Connect Audio Interface To Headphone Splitter / Amp Topics
- 0:00 – Introduction
- 0:10 – Why Connect Headphone Amp?
- 1:16 – Equipment We’re Using
- 1:55 – Pricing & Specs
- 2:05 – Balanced vs. Unbalanced Cable
- 3:02 – How To Use Balanced TRS Cable
- 4:09 – Connect Headphone Jack to Headphone Amp
- 7:13 – Connect Left Line Output to Headphone Amp
- 8:17 – Connect Both Line Outputs to Headphone Amp
- 9:18 – Summary
- 10:03 – Final Thoughts
