Do low impedance headphones really need less power?

You’ve probably heard people say this one before:

“Low impedance headphones need less power than high impedance ones.”

Sounds logical, right? 32 ohms should be easier to drive than 300 ohms?

Well… not exactly.

What actually determines power

Here’s the real deal:

Power = Voltage × Current

• Low impedance (like 32 Ω) draws more current.
• High impedance (like 300 Ω) needs more voltage.

See the balance? The lower the ohms, the higher the current demand. The higher the ohms, the higher the voltage demand.

There’s no free lunch here.

So when you see “32 ohms” and think your phone will drive it easily… not always.

Headphones also have frequency-dependent impedance curves, not just a flat number. Impedance varies with frequency, sometimes rather significantly.

Why specs can mislead you

You’ll often see “32 Ω, 105 dB SPL/mW” and think, “Cool, easy to drive.”

However, this is often not the case.

Some so-called “easy” 32-ohm models distorted like crazy on small DACs because they demanded too much current. Meanwhile, some high-impedance, high-sensitivity pairs played beautifully even on modest gear.

• Don’t assume low ohms means easy to drive.
• Check sensitivity (dB SPL/mW) first.
• Match your headphones to an amp that delivers more than enough voltage and current.
• If your sound gets loud but distorted, your amp is current-limited.

What is the solution?

If you’re ever in doubt, the easiest thing you can do is get a great headphone amp and stop worrying (at least for 99% of headphones).

The great news is that there are amazingly powerful and cheap amps out there. Here are the ones I usually recommend to my students, depending on their budget:

• Grace m900 (around 700 €): super portable, amazing build.
• Topping DX5II (300 €): best specs for the price, plus EQ.
• FiiO QX13 (230 €): super powerful, very affordable and portable.
• RME ADI-2/4 Pro SE (2480 €): my current amp.