Why do I need a headphone amplifier ?

More than 5 years ago, I was very surprised and a little amused when I have been informed that headphones need amplifiers to sound at full capacity.  With experience I have realized that is very true.

HeadPhone Amplifiers

I have said many times that some headphones are / should be considered a normal part of full blown sound system, not just something to use for portable use or just privacy.

Considering they are like little speakers and speakers need amplifiers to sound at their best or to produce sound at all, why shouldn’t headphones need them?

HeadRoom says it well here:

With good headphones, a good source, and a good headphone amp you’ll be pleasantly surprised at the level of audio performance you get. In fact, while speaker systems can out-perform headphones in terms of imaging and visceral impact, headphones can deliver much superior resolution and detail. The most common reaction folks have with their first experience listening to good headphones with a good amp is, “I’ve heard stuff I’ve never heard before, I’m going to have to listen to my whole music collection over again.”

First time I heard Sennheiser HD800 on Burson HA-160DS I wasn’t so impressed, but with Burson Conductor they started singing and impressed me so much I bought them. The amplifier in Conductor really woke them up.

I also remember my first listen with LCD-2 on Conductor. I felt like I reached their full potential with the Conductor and like I listened to them for the first time.

Now I am really impressed with Decware Taboo MK3, as it really improved transparency, sound fluency, soundstage, details, instrument extension and bass.

Hearing the Audio GD Master 9 was another revelation, as I have never heard a more transparent, detailed and natural amplifier.

If you have a very good DAC, you just have to get an amplifier that can let it shine, as if it alters/adds noise to the signal, you won’t get the most out of your DAC.

I see a lot of people that think that the amplifiers are just meant for higher volumes. This is not true. A good amplifier will improve the sound at any level bringing better dynamics, details, bass, transparency, etc

When I look for an amplifier I usually look for one that has a clean and simple circuit to keep the signal clean and not adding noise or taking away from transparency because of too many components in the design.

Power is a very important feature of a headphone amplifier but it is not the first or the only important thing, as it’s not just about the quantity of the signal as it should also be as clean as possible.

I usually look in an amplifier for:

  • Clean, good power supply
  • Power at different impedance levels (for example Burson originally stated that Conductor has 4W at 16 Ohms)
  • Clean and simple circuit
  • Output Impedance

The relationship between headphone impedance and the impedance of an amplifier is described well on innerfidelity:

The other factor is the relationship between the headphone impedance and the output impedance of the amplifier. As a general rule, the headphone impedance should be 10 times the output impedance of the amplifier. This is a complex subject, but in brief, when the amplifier’s output impedance is much lower than the headphone impedance you get good electrical damping of the headphones and they will sound tighter and more articulate. High-impedance cans with over 300 Ohms impedance like the Sennheiser HD 600 and HD 800 will be very happily driven by high-output impedance amps like output transformerless tube amps, which have output impedances in the few tens of Ohms. Custom In-Ear Monitors like the Jerry Harvey JH 13 with around 10 Ohms impedance are best served by a headphone amp with under 1 Ohm output impedance.

Also how to decide if your headphones need a headphone amplifier:

Headphones have a number of properties which will determine how much they need a headphone amplifier, but the most important are the efficiency/sensitivity, and the impedance.

The efficiency or sensitivity of a headphone indicates how loudly it will play given a certain amount of amplifier power. This specification SHOULD be stated as a certain decibel level achieved with 1 milliwatt (mW) of power. A VERY efficient headphone will provide 100 dB (or more) of output given 1mW of power from the amp. Typically this is the range an IEM will be in. And as such, a high efficiency headphone will be less likely to require a dedicated headphone amplifier, from a purely power/volume perspective.

Many non-portable, high end home headphones are less efficient, though, and some, like the currently popular planar magnetic headphones, are really not at all efficient, and require more than a few watts of power to generate the same output level that an high-efficiency IEM can generate from one milliwatt. Headphones with sensitivity specs in the 95dB or less range (as a very loose guide) are more likely to require a headphone amp.

The system is  formed by Source – > Amplifier -> Headphones, and it will be as good as the weakest link. The amplifier is a very important part of the chain.

Check out the headphone amplifiers recommendations page.