Sony’s MDR-CD900ST is a pair of closed-back monitor headphones.
Monitor headphones are headphones for hearing sound exactly as it is when you record or mix.
In this article we rate it on 5 criteria using only the specifications the manufacturer publishes, and show how it ranks among the 20 monitor headphones we compare.
Disclosure: This site takes part in affiliate programs. Specifications are as of the date we checked them and can change.
Score 4.2 / 5 (average of the 20 models compared: 3.6)
- Specs last checked
- 2026/10/19
- Type
- Closed-back
- Impedance
- 63Ω
- Weight
- 200g
- Upper limit
- 30,000Hz
- Price (store, date)
- Not disclosed
Figure: SoundBounty
Summary
Among the 20 monitor headphones, MDR-CD900ST is rank S. The ranks run S, A, B and C, and S is the top. Averaging the scores for each criterion (out of 5) gives 4.2.
Strengths
- Low-frequency range (5 Hz, 5 points): You can check the low end solidly.
- High-frequency range (30,000 Hz, 4 points): You can check the fine details of the highs.
- Lightness (200 g, 5 points): They are light and do not tire you over long periods.
- Suitability for recording (sound leakage) (closed-back design, 5 points): They leak little sound, so they can be used while recording vocals.
Things to keep in mind
- Ease of driving (63 Ω, 2 points): They need more power to reach a good volume, and with some equipment the volume may run short.
Who it suits: judging from the specifications, it suits people who want to check the low end solidly; people who want to check the fine details of the highs; people who want headphones that do not tire them over long periods.
Main features of MDR-CD900ST
A studio standard
Developed jointly by Sony and Sony Music Studios, this is a professional monitor headphone. It was originally made for use in the CBS Sony Shinanomachi studio, and has been used in many recording studios since its release in 1989. Sales to the general public began in 1990.
Resolution that shows the outline and position of sounds
With its dedicated driver unit, it is said to reproduce even small differences in the outline and placement of sounds (the position of a sound) and the spread of echo. It is said to aim for a sound with little distortion that is close to the original.
Built to stand up to studio use
Its maximum input of 1,000 mW and reinforced frame and covers are said to give it the durability to withstand use in studios and broadcasting stations. It weighs about 200 g.
A standard plug, and a note on repairs
The plug is a stereo standard plug and the cord is 2.5 m. It is sold by Sony Music Solutions, and because it is for professional use there is no free repair period; every repair is paid.
Where it is useful
- Hearing the backing track while recording vocals (closed-back)
- Checking sound at home with the same headphones used in studios
- Checking small noises and the position of sounds
Rating by criterion
Ease of driving: 2 / 5
Whether you can get volume without a headphone amplifier (impedance). The smaller the number, the easier they are to drive.
MDR-CD900ST: 63 Ω. That is a modest rating among the products we compared. They need more power to reach a good volume, and with some equipment the volume may run short.
Low-frequency range: 5 / 5
How low a sound they can reproduce (the lower limit of the frequency response).
MDR-CD900ST: 5 Hz. That is a high rating among the products we compared. You can check the low end solidly.
High-frequency range: 4 / 5
How high a sound they can reproduce (the upper limit of the frequency response).
MDR-CD900ST: 30,000 Hz. That is a high rating among the products we compared. You can check the fine details of the highs.
Lightness: 5 / 5
The weight of the headphones. The lighter they are, the less they tire you over long periods.
MDR-CD900ST: 200 g. That is a high rating among the products we compared. They are light and do not tire you over long periods.
Suitability for recording (sound leakage): 5 / 5
Whether they are closed-back, which leaks little sound. Less leakage means the headphone sound does not get into the microphone while you sing.
MDR-CD900ST: closed-back design. That is a high rating among the products we compared. They leak little sound, so they can be used while recording vocals.
The gray marks in the figure below (the dotted line on the pentagon) show the average of the 20 products we compared. Price is not part of the score.
How we score (Monitor headphones)
| Criterion | Basis | 5 pt | 4 pt | 3 pt | 2 pt | 1 pt |
|---|---|---|---|---|---|---|
| Ease of driving | Impedance (the lower it is, the easier to reach a good volume from a small amplifier) | ≤32 | ≤40 | ≤55 | ≤100 | >100 |
| Low-frequency range | Lower limit of the frequency response | ≤5 | ≤8 | ≤15 | ≤20 | >20 |
| High-frequency range | Upper limit of the frequency response | ≥40000 | ≥30000 | ≥25000 | ≥22000 | <22000 |
| Lightness | Weight (cable excluded) | ≤200 | ≤220 | ≤250 | ≤290 | >290 |
| Suitability for recording (sound leakage) | Closed-back or open-back (closed-back keeps sound out of the microphone while you sing) | Closed-back | — | — | — | Open-back |
Scored only on the body specifications published by the manufacturer. Price and accessories are not part of the score. Ease of driving is compared by impedance (Ω), which every manufacturer publishes. The lower the number, the easier it is to reach a good volume from the headphone jack of an audio interface or a smartphone, so a headphone amplifier is less likely to be needed (sensitivity is shown in the table for reference). "Suitability for recording" scores closed-back headphones higher because the sound is less likely to leak into the microphone while you sing. If you choose open-back headphones for mixing, you can ignore this item.
MDR-CD900ST connection and getting started
| Connection | Stereo standard plug (6.3 mm), 2.5 m cord (attached to the body) |
|---|---|
| Other | No free repair period (all repairs are paid, per Sony’s official page). To connect to the mini jack of a smartphone and similar devices, you need an adapter |
Checked on the manufacturer’s official pages on September 27, 2026.
Compared with other monitor headphones
Click a heading to sort. On a phone, the table scrolls sideways.
| Product | RankAvg. score | Type | ImpedanceΩ | SensitivitydB/V | Lower limitHz | Upper limitHz | Weightg | Price (store, date) |
|---|---|---|---|---|---|---|---|---|
| Audio-TechnicaATH-M20x | A 3.4 | Closed-back | 47 | 109.3 | 15 | 20,000 | 190 | Not disclosed |
| Audio-TechnicaATH-M30x | A 3.4 | Closed-back | 47 | 109.3 | 15 | 22,000 | 220 | Not disclosed |
| Audio-TechnicaATH-M40x | A 3.4 | Closed-back | 35 | 112.6 | 15 | 24,000 | 240 | Not disclosed |
| Audio-TechnicaATH-M50x | A 3.4 | Closed-back | 38 | 113.2 | 15 | 28,000 | 285 | Not disclosed |
| Audio-TechnicaATH-M70x | S 4.2 | Closed-back | 35 | 111.6 | 5 | 40,000 | 280 | Not disclosed |
| Audio-TechnicaATH-R70x | B 3.2 | Open-back | 470 | 101.3 | 5 | 40,000 | 210 | Not disclosed |
| SonyMDR-M1 | S 4.4 | Closed-back | 50 | 115 | 5 | 80,000 | 216 | Not disclosed |
| SonyMDR-M1ST | S 4.8 | Closed-back | 24 | 119.2 | 5 | 80,000 | 215 | Not disclosed |
| SonyMDR-CD900ST | S 4.2 | Closed-back | 63 | 118 | 5 | 30,000 | 200 | Not disclosed |
| YamahaHPH-MT8 | B 3.2 | Closed-back | 37 | 116.3 | 15 | 28,000 | 350 | Not disclosed |
| YamahaHPH-MT5 | B 2.8 | Closed-back | 51 | 112.9 | 20 | 20,000 | 245 | Not disclosed |
| beyerdynamicDT 770 PRO 80Ω | A 4.0 | Closed-back | 80 | Not disclosed | 5 | 35,000 | Not disclosed | Not disclosed |
| beyerdynamicDT 990 PRO 80Ω | B 3.0 | Open-back | 80 | Not disclosed | 5 | 35,000 | 250 | Not disclosed |
| SennheiserHD 280 PRO | B 3.2 | Closed-back | 64 | Not disclosed | 8 | 25,000 | 285 | Not disclosed |
| SennheiserHD 25 | B 3.2 | Closed-back | 70 | Not disclosed | 16 | 22,000 | 140 | Not disclosed |
| ShureSRH440A | B 3.2 | Closed-back | 40 | 111 | 10 | 22,000 | 268 | Not disclosed |
| ShureSRH840A | A 3.8 | Closed-back | 40 | 111 | 5 | 25,000 | 273 | Not disclosed |
| AKGK371 | S 4.4 | Closed-back | 32 | 114 | 5 | 40,000 | 255 | Not disclosed |
| beyerdynamicDT 770 PRO X | A 3.8 | Closed-back | 48 | Not disclosed | 5 | 40,000 | 305 | Not disclosed |
| SonyMDR-7506 | B 2.8 | Closed-back | 63 | 118 | 10 | 20,000 | 230 | Not disclosed |
Specifications are the manufacturer's published values (checked October 19, 2026). Sensitivity is written differently by each manufacturer, so it is shown for reference; beyerdynamic and the Sennheiser HD 280 PRO do not publish a sensitivity.
Before you buy
- They are closed-back. They leak little sound, so they are also easy to use for recording vocals.
- The impedance is 63 Ω. The impedance is on the low side, so it is relatively easy to reach a good volume even from the headphone jack of an audio interface. For reference, the sensitivity (loudness per 1 V) is 118 dB/V.
Read next
- K371: features and rating (rank S)
- SRH840A: features and rating (rank A)
- DT 770 PRO X: features and rating (rank A)
- ATH-R70x: features and rating (rank B)
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