A headphone amp is the best solution to optimize the power supply and audio quality of your headphones or in-ear monitors. But how do you connect a headphone amp in the most efficient way? How do you connect all the sources already associated with your hi-fi amplifier? Is it possible to connect your computer or smartphone to it? Find out how to properly connect a headphone amplifier to your equipment to enjoy the best possible listening experience.
Why use a headphone amp?
The headphone output built into amplifiers or CD players usually works fine, but it is often the poor relation when designing these devices, especially entry level models. Interference can degrade the sound signal, especially if the amplification of the headphone output is not isolated from the main circuit. For example, the operation noises of a CD player’s disc drive can be transmitted through the headphones. With amplifiers, the power supply is liable to create disturbances in the signal. Thus, whatever the qualities of the headphones used, it is possible to improve their musical performance by associating them with a headphone amplifier. The latter also has the advantage of better managing impedance variations between different headphones, especially the more demanding ones that require a fair amount of power to deliver their full potential. A headphone amplifier therefore allows you to benefit from better dynamics and optimized tone reproduction. Enough to make the most of a pair of high-end headphones.
How to connect a headphone amplifier to a hi-fi amplifier
If you have an existing hi-fi system, all your sources are probably already connected to a hi-fi amplifier. So how can you enjoy these sources on both your hi-fi amplifier and via your headphone amp, without having to constantly unplug each device? For this purpose, many stereo amplifiers offer two solutions: a pre-out and/or a REC output.
If you connect the headphone amplifier to the pre-out, the hi-fi amplifier will act as a pre-amplifier. In practice, you will be able to adjust the volume from both the hi-fi amp and the headphone amp. This configuration can be very convenient when your headphone amplifier does not have a remote control, as you can then easily control the volume remotely with the stereo amplifier’s remote control. However, care must be taken to keep the output level close to that accepted by the headphone amplifier’s input so as not to generate distortion. For this reason, it is often preferable to connect a headphone amplifier to the REC output of an amplifier, as the latter has a constant line level. There is therefore less risk of distortion and the volume can only be adjusted from the headphone amplifier.
Whether the headphone amplifier is connected to the REC output or pre-out of a hi-fi amplifier, it is better to use a high-quality RCA cable such as the Norstone Arran RCA to maximize the signal transfer from your different sources. Note that depending on the electrical installation, the association of a headphone amplifier can cause a ground loop problem resulting in unwanted noise from the speakers and headphones. In this case, it is necessary to isolate each element using a galvanic filter such as the Oehlbach Audio Linear 8.
How to connect a headphone amplifier to an AV receiver
The headphone output of A/V receivers is often of poor quality. The use of an external headphone amplifier is often essential to enjoy the best sound quality. To connect a headphone amplifier to an AV receiver, the best solution is to use the receiver’s Zone 2 output. The level of the latter can usually be set to fixed or variable. As with hi-fi amplifiers, it is best to opt for a fixed level to maximize the performance of the headphone amplifier. In addition, using the Zone 2 output allows you to enjoy an output that is independent of the rest of the A/V receiver, making it possible to listen to your music through headphones while someone else is watching TV.
How to connect a headphone amplifier to a computer
It is possible to connect a headphone amplifier to a computer using a mini-jack to RCA cable such as the Audioquest Golden Gate mini-jack RCA cable. Although practical, this solution is not the most efficient, because the music is converted and largely amplified by the computer’s sound card. The latter is often of poor quality, even on high-end computers. It is therefore best to use a headphone amplifier that has its own DAC and a USB input. Such models include the Cambridge DacMagic 200M, iFi Audio Zen Dac and iFi Audio iDSD Neo iDSD. Using a cable like the NorStone Jura USB A>B, you can then connect the amp to the computer’s USB port to bypass the sound card entirely. Using software such as Foobar or Audirvana, this configuration also allows you to enjoy Hi-Res music and DSD files that your computer cannot decode and read without losing information. An Audio DAC with a headphone amp function is therefore a sure way to enjoy the best music quality possible.
If your headphone amplifier is entirely analog and you still want to enjoy optimal sound quality with a computer, you can add a USB Audio DAC like the Micromega MyDAC. The latter has a USB-B input to support the conversion of music played from your computer. The headphone amplifier is then easily connected to its analog RCA output.
How to connect a headphone amplifier to a smartphone
For the most part, the latest smartphones aren’t equipped with a mini-jack output to allow you to connect a pair of headphones or in-ear monitors. Even if some still feature this output, it is often of average quality and its power is insufficient to power demanding headphones. It is therefore becoming increasingly common to have to connect a headphone amp to your smartphone to use hi-fi headphones in the best possible conditions. To do this, the connection is very similar to that used for computers. Consequently, you need a headphone amplifier with a USB input or a USB Audio DAC. The required cable, however, varies from one smartphone to another. For Android models, you need a USB-C to USB-B cable like the Audioquest Forest USB-B to USB-C, while Apple smartphones require the Apple Lightning to USB adapter.
For mobile use and to enjoy the qualities of your hi-fi headphones or IEMs when traveling, it is possible to pair your smartphone with a portable audio DAC or a portable headphone amplifier. The latter also connect to the smartphone’s USB port, the only difference being that they are more compact to fit in your pocket and do not need to be plugged into the mains. Some models such as the Astell & Kern PEE51 are no larger than a USB flash drive and are powered directly by the smartphone. More energy-intensive models like the iFi Audio hip-dac integrate their own battery so as not to impact the autonomy of the associated device.