Do I need a headphone amplifier?

Low-impedance headphones (16-32Ω) are often loud enough from a phone or laptop. High-impedance headphones (250-600Ω) almost always need a dedicated amp to reach satisfying volume and dynamics. The real issue is usually voltage, not raw wattage.

What is the 1/8th rule for output impedance?

The output impedance of your amp should be no more than 1/8th of your headphone impedance for a flat frequency response. For 32Ω headphones, the amp output impedance should be below 4Ω. Higher output impedance can alter the sound.

What is crest factor and why does it matter?

Crest factor is the difference between peak and average signal levels, typically 10-12 dB for music. Your amp needs to handle peaks without clipping. A 10 dB crest factor means your amp needs 10 times the average power for clean peaks.

How do sensitivity and impedance relate?

Sensitivity (dB/mW) tells you how loud the headphones get per milliwatt of power. Higher sensitivity = louder at the same power. Impedance affects how much voltage and current the amp needs to deliver that power. High impedance needs more voltage, low impedance needs more current.

AudioCalcs

Headphone Amp Calculator — Power Requirements

Calculate headphone amplifier power, voltage and current requirements for your headphones.

Headphone ImpedanceElectrical impedance in ohms

Sensitivity

Check headphone specifications

Desired Listening Level85 dB ≈ comfortable monitoring; 100 dB = reference/peak. Crest-factor headroom is added on top.

Number of Headphones

For multi-headphone setups

How We Calculate This

Calculation Method

Power (mW) = 10^((Target SPL − Sensitivity + Crest factor) / 10)
Voltage (Vrms) = √(Power × Impedance)
Current (mA) = Voltage / Impedance × 1000
Max output impedance = Headphone impedance / 8 (1/8th rule)

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Last updated: March 2026

All calculations are estimates based on standard formulas. Always verify results for critical applications.