How Much Power Do Your Headphones Really Need?

If we only look at consumer grade headphones designed for smartphones and laptops, not that much. However, once you step into the world of audiophile gear, the relationship between headphones and amplifiers gets more complicated.

More Impedance = Need More Power?

A common misconception is that the higher the impedance of the headphones, the beefier your amplifier should be. This is sometimes true, but not always. To really understand how much power our headphones need, we first need to understand some basic terminology. 

• Voltage (V) Think of this as electrical pressure. It’s the force pushing the charge through the circuit. It’s like the water pressure in a hose. The higher the pressure, the quicker the water moves. 
• Current (I) This measures the flow of the electrons. If the voltage is the pressure, then the current is the volume–how much water is flowing through the hose per second This is measured in amperes.
• Impedance (Ω) This represents electrical resistance. You can imagine this as the diameter of the hose. A narrow hose makes it harder for water to flow, while a wider hose makes it easier. This is measured in Ohms.
• Sensitivity (dB/V) This tells you exactly how loud the headphones get for every volt you give them. Some get loud very easily, while some need more “push”. 
• Efficiency (db/mW) Tells you how loud headphones get per milliwatt, which is useful if you are shopping for an amp. Imagine this like miles per gallon for headphones—how much “loudness” you get from a small amount of power.

A high-impedance headphone is a narrow hose that needs high pressure/voltage to get the water moving from one end to the other. A low-impedance headphone is a wide hose that needs a high volume/current of water to fill it up. Your volume pot is the adjustable nozzle in this analogy.

Manufacturers usually keep consumer gear low-impedance by design so a phone’s or laptop’s limited output can actually drive them. Once you move into high-end gear, though, these limits matter less because dedicated amps have the voltage and current to spare.

Sensitivity and Efficiency Matter More

While impedance is a factor, sensitivity and efficiency dictate the specific power requirements of your headphones. Take a look at some samples below.

Higher sensitivity and efficiency figures are almost always better. They guarantee the headphones will sound great across a wider range of devices without requiring a dedicated amp. It is also easier to form an educated guess with sensitivity, since it references 1 volt.

• ¹Has decent sensitivity, but requires more voltage. Some motherboards and USB DAC/Amps could drive them well.

• ²Scales well with good amplifiers such as the Apos x Gremlin (Shameless plug, I know).

• ³IEMs with similar specs are too efficient, you may hear the noise floor. A good DAC is a must.

Leave Headroom to Breathe

Audio signals fluctuate to create sound. A snare or a sudden bass drop can be magnitudes louder than the average listening volume. If an amplifier already has its volume pot maxed at listening level, it'll definitely clip the signal during peaks. Clipping cuts off the top of the sound wave, making your music sound distorted.

To keep audio output clean, aim for 18-24 dB of headroom above your listening level. Professional standards, such as the European Broadcasting Union (EBU), emphasize maintaining this dynamic range to ensure peaks don't hit the ceiling. 

I normally listen at approximately 86 dB, so I want an amp that can cleanly reach at least 104-110 dB when paired with a capable headphone.

To Buy or not to Buy

Don't let a big number force you into a $$$ purchase. Check the sensitivity first. If your headphones sit in our table’s easy to moderate range, a laptop or a basic dongle will probably handle them fine.

If you're eyeing the harder-to-drive pairs, grab a dedicated amp. It'll drive almost anything on the market with enough dynamic range and headroom.

This may leave you with more questions than answers, and if so, start the chat below on our forum!