Published October 2026 · figures checked Oct 30, 2026. Every source figure is a manufacturer rating or a third-party measurement, named in the table below. AmperHeads does not bench-test gear. How we research .
Pick your headphone and your source. The calculator shows how much voltage and power the headphone needs for loud peaks, what the source can deliver into that load, and how much headroom is left. If the verdict says you need an amp, the button takes you to the pairing guide for that headphone.
- Needed for that peak
- With 6 dB headroom
- Source delivers into this load
- Loudest clean peak
- Headroom
Source figure:
Amp pairing guidesHow to Read the Result
- Needed for that peak: the power, voltage and current the headphone needs to reach your target peak (110 dB by default).
- Source delivers into this load: the source’s maximum clean output voltage into your headphone’s impedance, from its published power ratings. Where a maker publishes ratings at 32Ω and 300Ω, the calculator interpolates between them. Where it doesn’t publish a rating close to your headphone’s impedance, the result is marked “approx.”.
- Headroom: how far above your target peak the source can go before it runs out. +6 dB or more is comfortable. 0 to +6 dB is enough with little reserve. Below 0, loud passages compress.
- Z/8 note: shown when the source’s output impedance is too high for the headphone (more than one eighth of its impedance). That matters for dynamic headphones such as the Sennheiser HD 600 or Beyerdynamic DT 990; planars like the HE400SE are hardly affected.
Want the background first? What is headphone impedance explains why a 300Ω headphone needs voltage and a 25Ω planar needs current, and do I need a headphone amp covers when an amp changes anything at all.
The Math
All figures use the headphone maker’s own impedance and sensitivity, the same numbers our pairing guides use.
- Power for the target peak: P (mW) = 10^((target − sensitivity in dB/mW) ÷ 10)
- Voltage: V = √(P in watts × impedance)
- Current: I = V ÷ impedance
- Headroom: the loudest peak the source can reach, sensitivity + 10 × log10(V² ÷ impedance × 1000), minus your target.
A worked example: the Sennheiser HD 600 is rated 300Ω and 97 dB/mW. For 110 dB peaks it needs 10^(13 ÷ 10) = 20 mW, √(0.020 × 300) = 2.45 V and 8 mA. The Apple USB-C adapter delivers about 1 V, which reaches about 102 dB, so it falls about 8 dB short. A Schiit Magni (Unity) delivers about 11 V into 300Ω, about 13 dB more than needed. That is the whole case for a desktop amp on the HD 600, and the HD 600 amp guide goes through every current option.
What Popular Headphones Need
Calculated for 110 dB peaks from the published specs. The last column is the highest source output impedance that keeps a dynamic headphone’s tuning intact.
| Headphone | Impedance | Sensitivity | For 110 dB peaks | Voltage with 6 dB headroom | Max source Zout (Z/8) |
|---|---|---|---|---|---|
| Sennheiser HD 600 | 300Ω | 97 dB/mW | 20 mW · 2.45 V · 8 mA | 4.89 V | 37.5Ω |
| Sennheiser HD 650 / HD 6XX | 300Ω | 97 dB/mW | 20 mW · 2.45 V · 8 mA | 4.89 V | 37.5Ω |
| Sennheiser HD 660S2 | 300Ω | 99 dB/mW | 13 mW · 1.94 V · 6 mA | 3.89 V | 37.5Ω |
| Sennheiser HD 560S | 120Ω | 101 dB/mW | 7.9 mW · 0.98 V · 8 mA | 1.95 V | 15.0Ω |
| Sennheiser HD 550 | 150Ω | 98.5 dB/mW | 14 mW · 1.46 V · 10 mA | 2.91 V | 18.8Ω |
| Sennheiser HD 505 | 120Ω | 98.7 dB/mW | 13 mW · 1.27 V · 11 mA | 2.54 V | 15.0Ω |
| Sennheiser HD 490 Pro | 130Ω | 96 dB/mW | 25 mW · 1.81 V · 14 mA | 3.61 V | 16.2Ω |
| Sennheiser HD 800 S | 300Ω | 96.8 dB/mW | 21 mW · 2.50 V · 8 mA | 5.01 V | 37.5Ω |
| Sennheiser HD 58X Jubilee | 150Ω | 98 dB/mW | 16 mW · 1.54 V · 10 mA | 3.08 V | 18.8Ω |
| Beyerdynamic DT 770 Pro 32Ω | 32Ω | 96 dB/mW | 25 mW · 0.90 V · 28 mA | 1.79 V | 4.0Ω |
| Beyerdynamic DT 770 Pro 80Ω | 80Ω | 96 dB/mW | 25 mW · 1.42 V · 18 mA | 2.84 V | 10.0Ω |
| Beyerdynamic DT 770 Pro 250Ω | 250Ω | 96 dB/mW | 25 mW · 2.51 V · 10 mA | 5.01 V | 31.2Ω |
| Beyerdynamic DT 770 Pro X | 48Ω | 98 dB/mW | 16 mW · 0.87 V · 18 mA | 1.74 V | 6.0Ω |
| Beyerdynamic DT 990 Pro 250Ω | 250Ω | 96 dB/mW | 25 mW · 2.51 V · 10 mA | 5.01 V | 31.2Ω |
| Beyerdynamic DT 1990 Pro | 250Ω | 102 dB/mW | 6.3 mW · 1.26 V · 5 mA | 2.51 V | 31.2Ω |
| Audio-Technica ATH-M50x | 38Ω | 99 dB/mW | 13 mW · 0.69 V · 18 mA | 1.38 V | 4.8Ω |
| Sony MDR-7506 | 63Ω | 106 dB/mW | 2.5 mW · 0.40 V · 6 mA | 0.80 V | 7.9Ω |
| AKG K712 Pro | 62Ω | 93 dB/mW | 50 mW · 1.76 V · 28 mA | 3.53 V | 7.8Ω |
| HiFiMAN HE400SE | 25Ω | 91 dB/mW | 79 mW · 1.41 V · 56 mA | 2.82 V | 3.1Ω |
| HiFiMAN Sundara | 37Ω | 94 dB/mW | 40 mW · 1.21 V · 33 mA | 2.43 V | 4.6Ω |
| HiFiMAN Edition XS | 18Ω | 92 dB/mW | 63 mW · 1.07 V · 59 mA | 2.13 V | 2.2Ω |
Three groups stand out:
- Easy loads (MDR-7506, DT 770 Pro X, ATH-M50x, DT 770 Pro 32Ω and 80Ω): about 1.4 V or less, so a phone, dongle, laptop or controller is enough. The DT 770 Pro vs Pro X comparison works through console and phone sources in detail.
- High-impedance dynamics (HD 600, HD 650, HD 660S2, DT 990 Pro 250Ω, DT 1990 Pro): 2 to 2.5 V. They play from a phone but run out of headroom, which is why they have a reputation for “needing an amp”.
- Planars (HE400SE, Sundara, Edition XS): modest voltage but more current, 50 to 80 mA. Dongles and phones that are current-limited at low impedance are the weak point; any desktop amp clears them. The planar vs dynamic guide explains the difference.
Source Figures Used
Volts derived from each maker’s power rating as √(power × load). “n/a” means the maker doesn’t publish a rating at that load; the calculator then uses the nearest published figure and marks the result “approx.”.
| Source | Into 32Ω | Into 300Ω | Output impedance | Basis |
|---|---|---|---|---|
| Apple USB-C to 3.5 mm adapter | 0.98 V | 1.00 V | 1Ω | About 1 V; ~30 mW into 32Ω (Audio Science Review measurements) |
| PS5 DualSense controller jack | 1.00 V | 1.00 V | 1Ω | About 1 V or less (upper estimate; Sony publishes no figure) |
| Laptop / motherboard 3.5 mm (typical) | 1.00 V | 1.00 V | 5Ω | About 1 V typical; output impedance varies from ~1Ω to 30Ω+ |
| Focusrite Scarlett 2i2 (4th gen) | n/a | 1.70 V | 1Ω | About +7 dBu ≈ 1.7 V (Focusrite spec); low-impedance figure not published |
| FiiO K11 R2R, 6.35 mm | 3.84 V | 3.87 V | 1Ω | 660 mW / 16Ω, 460 mW / 32Ω, 50 mW / 300Ω (FiiO) |
| FiiO K11 R2R, 4.4 mm balanced | 6.45 V | 8.10 V | 1.5Ω | 520 mW / 16Ω, 1.3 W / 32Ω, 220 mW / 300Ω (FiiO) |
| Schiit Magni (Unity) | 8.94 V | 11.20 V | 0.1Ω | 3 W / 16Ω, 2.5 W / 32Ω, 415 mW / 300Ω (Schiit) |
| JDS Labs Atom Amp 2 | 9.20 V | 9.27 V | 0.7Ω | 2.65 W / 32Ω, 286 mW / 300Ω (JDS Labs) |
| Topping DX5 II, 6.35 mm | 8.40 V | 8.66 V | 1Ω | 3.3 W / 16Ω (as listed in reviews), 2.2 W / 32Ω, 250 mW / 300Ω (Topping) |
| Topping DX5 II, balanced | 14.30 V | 17.20 V | 1Ω | 7.6 W / 16Ω (reviews), 6.4 W / 32Ω, 990 mW / 300Ω (Topping) |
| Schiit Asgard X, ¼-inch | n/a | 10.70 V | 0.7Ω | 3.4 W / 16Ω, 380 mW / 300Ω (Schiit) |
| FiiO K7, 6.35 mm | 6.25 V | n/a | 1Ω | 1.22 W / 32Ω (FiiO); high-impedance figure not published, so treat 300Ω results as a minimum |
A few caveats:
- Phones, laptops and controllers don’t come with reliable published output figures. About 1 V is typical for a good one; EU volume-limited devices and many laptops sit closer to 0.5 V. Treat those rows as a best case.
- The FiiO K11 R2R’s balanced output is the stronger one into 300Ω but the weaker one into 16Ω, by FiiO’s own ratings. The calculator follows the ratings, so try both rows if you own one.
- Ratings are maximums. They describe the clean ceiling, not what you hear at normal volume. Headroom is about avoiding compression on peaks, not about sound “quality” at moderate levels.
When the Calculator Says You Need an Amp
Start with the guide for your headphone. Each one lists current amps by budget with the same math:
- Best amp for the Sennheiser HD 650 / HD 6XX
- Amps for the Beyerdynamic DT 990 Pro
- Driving the HiFiMAN HE400SE properly
- Every amp pairing guide
If you don’t have a specific headphone in mind yet, the best headphone amps under $200 and the DAC/amp combos under $300 cover the most common budgets.
Final Word
Most people asking “do I need an amp?” have one of two headphones: a 250 to 300Ω dynamic (HD 600 family, 250Ω Beyerdynamics) or a budget planar. Both play from a phone and both run out of room on loud, dynamic music. Everything else on the list above is happy with the jack you already have. Run your own numbers, and if you’re more than a few decibels short, a $119 to $170 desktop amp fixes it with 10 dB or more to spare.
Sources
- Manufacturer specifications: Sennheiser, Beyerdynamic, HiFiMAN, Audio-Technica, Sony, AKG, Schiit, JDS Labs, FiiO, Topping, Focusrite (figures as quoted in our pairing guides, each with its source).
- Apple USB-C to 3.5 mm adapter output: Audio Science Review measurements, as cited in our HD 600 pairing guide.