Short answer: the Stax SR-X9000. It ranks #101 of 216 over-ear headphones by sound quality, rated 3.8/5, at $6,819.99. The Abyss AB1-266 Phi TC ranks #116, rated 3.6/5, at $5,995, $824.99 cheaper, a saving that is not big enough to make up the sound-quality gap.
Why pick the Stax SR-X9000: A preference score of 77, with the midrange from 200 Hz to 3 kHz staying within about 1.3 dB of target for natural, uncolored voices and instruments. The catch: It needs a dedicated electrostatic energizer, and bass falls 6 dB below target by 56 Hz, about 9.5 dB short across the sub-bass, so the deepest notes are faint.
What the Abyss AB1-266 Phi TC does well: Oratory1990’s measurement gives it a preference score of 73, and air above 10 kHz is lifted about 3 dB, giving cymbals and room sound a light, airy sheen. Watch for: Bass sits about 6 dB below target under 60 Hz and 3 dB low from 60 to 200 Hz, so kick drums and bass lines sound thin, and treble from 6 to 10 kHz is about 6 dB low with a 10 dB dip near 6.5 kHz that veils detail.
Buy the Stax SR-X9000. It is rated higher for sound quality, and saving $824.99 with the Abyss AB1-266 Phi TC does not make up for the sound-quality gap.
Still deciding? The full Headphones rankings cover every ranked option.
Specifications Side By Side
| Stax SR-X9000 | Abyss AB1-266 Phi TC | |
|---|---|---|
| Price | $6,819.99 | $5,995.00 |
| Ranked | #101 of 216 in Over-Ear Headphones | #116 of 216 in Over-Ear Headphones |
| Form Factor | Over-ear | Over-ear |
| Harman Preference Score | 77 (measured by oratory1990, via AutoEQ) | 73 (measured by oratory1990, via AutoEQ) |
| Deviation From Target | 2.72 dB standard deviation | 2.81 dB standard deviation |
| Tonal Tilt | +0.20 (negative is warmer, positive brighter) | -0.39 (negative is warmer, positive brighter) |
| Sub-bass Extension | Falls 6 dB below target at 56 Hz (-9.0 dB at 30 Hz) | Within 6 dB of target down to 20 Hz (-5.7 dB at 30 Hz) |
| Connection | Wired | Wired |
| Back | Open | Open |
| Driver Type | Electrostatic | Planar magnetic |
| Drivers | 1 x large round push-pull electrostatic | 1 x 66mm planar magnetic |
| Sensitivity | 100 dB | 88 dB/mW |
| Weight | 1 lbs (432 g) | 1.4 lbs (640 g) |
| Frequency Response | 5Hz - 42kHz (Manufacturer specified) | 5Hz - 45kHz (Manufacturer specified) |
| Built-in Microphone | No | No |
| Impedance | - | 50 ohms |
Related Headphone Comparisons
More top alternatives to Stax SR-X9000:
- HIFIMAN Shangri-La Jr vs Stax SR-X9000
- HIFIMAN Susvara Unveiled vs Stax SR-X9000
- HIFIMAN Susvara vs Stax SR-X9000
- Warwick Acoustics Aperio vs Stax SR-X9000
- Abyss AB1-266 Phi TC vs T+A Solitaire PSE
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
Stax SR-X9000: $6,819.99 Elusive Disc eBay
Pros: A preference score of 77, with the midrange from 200 Hz to 3 kHz staying within about 1.3 dB of target for natural, uncolored voices and instruments. Air above 10 kHz rises 1.7 dB, adding openness to the top end, and the neutral, slightly warm balance suits critical listening. It earns a higher rating than the Focal Utopia 2022.
Cons: It needs a dedicated electrostatic energizer, and bass falls 6 dB below target by 56 Hz, about 9.5 dB short across the sub-bass, so the deepest notes are faint. A 14.1 dB dip near 9.7 kHz dulls cymbals and detail. The Final Audio D8000 Pro Edition and Dan Clark Audio EXPANSE cost much less and rate higher.
Full Stax SR-X9000 review and specifications →
| Released | 2021 (5 years ago) |
|---|---|
| Back | Open |
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 2.72 dB standard deviation |
| Driver Type | Electrostatic |
| Drivers | 1 x large round push-pull electrostatic |
| Form Factor | Over-ear |
| Frequency Response | 5Hz - 42kHz (Manufacturer specified) |
| Harman Preference Score | 77 (measured by oratory1990, via AutoEQ) |
| Sensitivity | 100 dB |
| Sub-bass Extension | Falls 6 dB below target at 56 Hz (-9.0 dB at 30 Hz) |
| Tonal Tilt | +0.20 (negative is warmer, positive brighter) |
| Weight | 1 lbs (432 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 | +5.7 dB | 0.70 |
| Peak | 1,081 Hz | -5.9 dB | 1.99 |
| Peak | 2,699 Hz | +2.5 dB | 1.47 |
| Peak | 201 Hz | -0.9 dB | 1.69 |
| Peak | 5,305 Hz | +2.1 dB | 6.00 |
| High shelf | 10,000 Hz | -4.2 dB | 0.70 |
| Peak | 7,973 Hz | +2.4 dB | 1.92 |
| Peak | 71 Hz | -1.7 dB | 3.73 |
| Peak | 6,342 Hz | -1.8 dB | 6.00 |
| Peak | 45 Hz | +1.0 dB | 4.46 |
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Abyss AB1-266 Phi TC: $5,995.00 Abyss eBay
Pros: Oratory1990’s measurement gives it a preference score of 73, and air above 10 kHz is lifted about 3 dB, giving cymbals and room sound a light, airy sheen. The open-back 66mm planar magnetic driver suits listeners who prefer a relaxed, laid-back presentation. It matches the rating of the Audeze LCD-5 and is rated above the Focal Utopia 2022.
Cons: Bass sits about 6 dB below target under 60 Hz and 3 dB low from 60 to 200 Hz, so kick drums and bass lines sound thin, and treble from 6 to 10 kHz is about 6 dB low with a 10 dB dip near 6.5 kHz that veils detail. At 88 dB/mW sensitivity it needs a capable headphone amp, it weighs 640 g, and the open back leaks sound and offers no isolation. The Stax SR-009S is rated higher for less money. See headphone amps and DACs with enough power to drive it.
Full Abyss AB1-266 Phi TC review and specifications →
| Back | Open |
|---|---|
| Built-in Microphone | No |
| Connection | Wired |
| Deviation From Target | 2.81 dB standard deviation |
| Driver Type | Planar magnetic |
| Drivers | 1 x 66mm planar magnetic |
| Form Factor | Over-ear |
| Frequency Response | 5Hz - 45kHz (Manufacturer specified) |
| Harman Preference Score | 73 (measured by oratory1990, via AutoEQ) |
| Impedance | 50 ohms |
| Sensitivity | 88 dB/mW |
| Sub-bass Extension | Within 6 dB of target down to 20 Hz (-5.7 dB at 30 Hz) |
| Tonal Tilt | -0.39 (negative is warmer, positive brighter) |
| Weight | 1.4 lbs (640 g) |
EQ preset to match the Harman target
Set a preamp of -5.9 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 | +3.6 dB | 0.70 |
| Peak | 1,064 Hz | -5.3 dB | 1.29 |
| Peak | 3,885 Hz | +5.4 dB | 2.10 |
| Peak | 236 Hz | -2.3 dB | 1.36 |
| Peak | 1,952 Hz | +3.7 dB | 3.03 |
| High shelf | 10,000 Hz | -9.6 dB | 0.70 |
| Peak | 8,198 Hz | +5.2 dB | 0.96 |
| Peak | 5,233 Hz | -4.8 dB | 5.05 |
| Peak | 1,416 Hz | -0.4 dB | 4.94 |
| Peak | 2,854 Hz | -1.2 dB | 4.61 |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons