How do I know if my headphones need an amp?
Two main factors: impedance and sensitivity. High impedance (250Ω+) headphones need more voltage to reach adequate volume. Low sensitivity (<95 dB/mW) headphones need more power. If your source can't provide enough, you need an amp.
What's the difference between impedance and sensitivity?
Impedance (Ω): Resistance to electrical current. Higher impedance needs more voltage.
Sensitivity (dB/mW or dB/V): How loud the headphones get per unit of power. Lower sensitivity needs more power to reach the same volume.
Can high-impedance headphones damage my phone?
No, high-impedance headphones are safe for any source—they just won't get very loud. The phone simply can't provide enough voltage, so you'll hit max volume before reaching satisfying levels. No damage occurs.
What is damping factor and why does it matter?
Damping factor is the ratio of headphone impedance to source output impedance. A ratio of 8:1 or higher ensures the amp can control the headphone drivers properly, resulting in tighter bass. Low damping factor can cause loose, boomy bass.
Do I need an expensive amp?
Not necessarily. For most headphones under 150Ω, a good $50-100 USB DAC/amp (like the FiiO E10K or iFi Zen DAC) is sufficient. High-impedance headphones (300Ω+) and planar magnetics benefit more from dedicated desktop amps in the $200+ range.
What about DAC vs Amp—do I need both?
A DAC converts digital audio to analog. An amp increases power/voltage. Most dedicated devices combine both. If your source already sounds clean (no hiss/noise), you mainly need more power. If you hear noise or distortion, a DAC upgrade helps too.