Short answer: the Stax SR-X1. Both are rated 4.0/5 for sound quality (#72 and #75 of 216 over-ear headphones), and the Stax SR-X1 costs $571.79 against $589.99 for the Fosi Audio i5, with sound quality a draw, the lower price decides it.
What the Fosi Audio i5 does well: A large 97mm planar magnetic driver scores 80.7 for preference in the median of four squig.link measurements, with the low mids about 1 dB over target for a full, warm tone. Watch for: Sub-bass drops roughly 5.8 dB below target and is already 6 dB down by 42 Hz, so deep synth bass and kick drum rumble lack impact.
Why pick the Stax SR-X1: A preference score of 81 in oratory1990’s measurement is excellent for an electrostatic headphone, with a smoothness of 2.62 dB and a neutral tilt of 0.06. The catch: Sub-bass under 60 Hz is about 8 dB below target and the bass range is 4 dB low, so kick drums and bass synths lack rumble and weight.
Buy the Stax SR-X1. Both are rated the same for sound quality, and it costs $18.20 less than the Fosi Audio i5.
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Specifications Side By Side
| Fosi Audio i5 | Stax SR-X1 | |
|---|---|---|
| Price | $589.99 | $571.79 |
| Ranked | #75 of 216 in Over-Ear Headphones | #72 of 216 in Over-Ear Headphones |
| Form Factor | Over-ear | Over-ear |
| Harman Preference Score | 81 (median of 5 squig.link measurements, calibrated to AutoEQ) | 81 (measured by oratory1990, via AutoEQ) |
| Deviation From Target | 2.17 dB standard deviation | 2.62 dB standard deviation |
| Tonal Tilt | -0.28 (negative is warmer, positive brighter) | +0.06 (negative is warmer, positive brighter) |
| Sub-bass Extension | Falls 6 dB below target at 40 Hz (-6.6 dB at 30 Hz) | Falls 6 dB below target at 40 Hz (-7.2 dB at 30 Hz) |
| Connection | Wired | Wired |
| Back | Open | Open |
| Driver Type | Planar magnetic | Electrostatic |
| Drivers | 1 x 97mm planar magnetic | - |
| Impedance | 28 ohms | - |
| Sensitivity | 98 dB/mW | 101 dB SPL/100V |
| Weight | 1.2 lbs (550 g) | 0.5 lbs (234 g) |
| Frequency Response | 10Hz - 50kHz (Manufacturer specified) | 7Hz - 41kHz (Manufacturer specified) |
| Built-in Microphone | No | - |
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- HIFIMAN Arya Stealth vs Stax SR-X1
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- HIFIMAN Arya Stealth vs Fosi Audio i5
- Fosi Audio i5 vs HIFIMAN Audivina
Prices on this page were last checked October 11, 2026 at 4:59 PM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Headphones In Full
Fosi Audio i5: $589.99 Amazon eBay
Pros: A large 97mm planar magnetic driver scores 80.7 for preference in the median of four squig.link measurements, with the low mids about 1 dB over target for a full, warm tone. Air above 10 kHz runs about 4.4 dB hot, which adds openness and detail to strings and cymbals. At 28 ohms and 98 dB/mW it is easier to drive than many planars and works from a modest desktop DAC or a capable dongle.
Cons: Sub-bass drops roughly 5.8 dB below target and is already 6 dB down by 42 Hz, so deep synth bass and kick drum rumble lack impact. A 5.8 dB dip near 2.2 kHz and a presence region about 3.2 dB low push vocals back, while the 5.1 dB peak at 10.9 kHz can sound splashy. It weighs 550 g, and the open back leaks sound and blocks no outside noise.
Full Fosi Audio i5 review and specifications →
| Released | Apr 2025 (1 year ago) |
|---|---|
| Back | Open |
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 2.17 dB standard deviation |
| Driver Type | Planar magnetic |
| Drivers | 1 x 97mm planar magnetic |
| Form Factor | Over-ear |
| Frequency Response | 10Hz - 50kHz (Manufacturer specified) |
| Harman Preference Score | 81 (median of 5 squig.link measurements, calibrated to AutoEQ) |
| Impedance | 28 ohms |
| Sensitivity | 98 dB/mW |
| Sub-bass Extension | Falls 6 dB below target at 40 Hz (-6.6 dB at 30 Hz) |
| Tonal Tilt | -0.28 (negative is warmer, positive brighter) |
| Weight | 1.2 lbs (550 g) |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Stax SR-X1: $571.79 Amazon eBay
Pros: A preference score of 81 in oratory1990’s measurement is excellent for an electrostatic headphone, with a smoothness of 2.62 dB and a neutral tilt of 0.06. Midrange from 1 to 3 kHz sits within 0.1 dB of target, so vocals and instruments sound natural, and air above 10 kHz is on target at +0.6 dB. It is open back and light at 234 g, a good match for the warm and neutral taste profiles.
Cons: Sub-bass under 60 Hz is about 8 dB below target and the bass range is 4 dB low, so kick drums and bass synths lack rumble and weight. A 9.4 dB dip near 6.5 kHz and treble 7 dB under target soften cymbals and make the sound dull. It needs a dedicated electrostatic energizer, since it cannot run from a phone, and the open back leaks sound and offers no isolation.
Full Stax SR-X1 review and specifications →
| Back | Open |
|---|---|
| Connection | Wired |
| Deviation From Target | 2.62 dB standard deviation |
| Driver Type | Electrostatic |
| Form Factor | Over-ear |
| Frequency Response | 7Hz - 41kHz (Manufacturer specified) |
| Harman Preference Score | 81 (measured by oratory1990, via AutoEQ) |
| Sensitivity | 101 dB SPL/100V |
| Sub-bass Extension | Falls 6 dB below target at 40 Hz (-7.2 dB at 30 Hz) |
| Tonal Tilt | +0.06 (negative is warmer, positive brighter) |
| Weight | 0.5 lbs (234 g) |
EQ preset to match the Harman target
Set a preamp of -6.3 dB, then add these filters in any parametric equalizer (Wavelet, Equalizer APO, Peace, or a player with parametric EQ). Calculated by AutoEQ from its measured frequency response.
| Filter | Frequency | Gain | Q |
|---|---|---|---|
| Low shelf | 105 Hz | +7.5 dB | 0.70 |
| Peak | 1,236 Hz | -4.1 dB | 1.22 |
| Peak | 7,163 Hz | +5.4 dB | 2.20 |
| Peak | 4,125 Hz | +2.9 dB | 4.23 |
| Peak | 55 Hz | -2.4 dB | 0.43 |
| High shelf | 10,000 Hz | -6.0 dB | 0.70 |
| Peak | 233 Hz | -0.5 dB | 2.53 |
| Peak | 553 Hz | +0.3 dB | 1.42 |
| Peak | 6,608 Hz | +1.9 dB | 5.85 |
| Peak | 5,454 Hz | -1.1 dB | 6.00 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons