Review and testing of audiophile player Hifiman HM-901s

With support for Hi-Res DSD 24/192, based on two ES9018S DACs and interchangeable amplifiers

Players of this series, the company Hifiman has developed according to the wishes of its audience, asking it for what functions users would like to see in an expensive player. Most asked for a capacious battery with a high swing voltage to exclude high-frequency voltage converters and possible problems from this. They asked for the most simple mechanical control, the lack of equalizers and treatments. And, of course, the maximum sound quality, as possible in a portable device. Users were ready to suffer, even if it leads to an increase in the size and weight of the player. Thus, the players Hifiman made clearly for the audience of the fans is an autonomous player. They do not beat records in size and weight, they do not have a Retina display, but instead they offer great sound and a lot of interesting even for owners of top models of full-size headphones.

The Hifiman HM-901s player is a silver (silver) modification of the famous top player Hifiman HM-901. The model with the prefix s is not only intended to expand the choice of appearance, but also contains quite a few changes. As a more luxury model, it costs more.

The player 901 warmed up during operation, so it had many holes for cooling on the sides. 901s, on the other hand, has a minimum of any holes and switches, and heat is diverted through the metal frame of the case and the metal outer covers. Inside, all the chips have a thermal interface for efficient heat removal.


Hifiman HM-901s

Hifiman HM-901s – price. Where is the best place to buy?

The recommended retail price for the Hifiman HM-901s in the US is about $ 1 499,00. At this cost, you can order it on Amazon. Plus Shipping, so the total cost of Hifiman HM-901s when ordering on Amazon will be about $ 1 520,00. I would not recommend ordering anywhere else except on Amazon. Since you are less likely to find cheaper, and if you do not take into account the fact that Amazon is probably the most reliable online store, it still very often provides free shipping.

Technical characteristics of Hifiman HM-901s

  • DAC: dual mono ESS Saber 32 ES9018S
  • Operational amplifier: 2 × OPA627, 2 × OPA2107
  • KG: 0.008% (linear output)
  • Signal / Noise: 106 dB
  • SD capacity: 256 GB
  • Running time: 9 hours
  • Formats: MP3, AAC, WMA, OGG, APE, WAV, FLAC, AIFF, ALAC, DSD64 (DFF, DSF)
  • Official hifiman.ru/products/hifi-players/hm-901s product page

As you can see, the emphasis is on the filling, but not on record characteristics. Let’s analyze the most interesting – stuffing.

Components

Hifiman HM-901s
Hifiman HM-901s

Features of the model a few. In addition to the dual mono DAC ESS Saber 32 ES9018S (the most expensive desktop version), it is already difficult to surprise the sophisticated music lover, this player also has replaceable headphone amplifiers.

Removable amplifiers are supported in several models of Hifiman players, but you need to look at the compatibility of a specific model of the amplifier with the player. Older motherboards are incompatible with the new generation of players.

Hifiman HM-901s

But the most interesting is that these modules change the capabilities of the player in terms of power and sound, which gives users a huge field for experiments. The only downside is that they are not cheap, from $ 100 to $ 300 for a fee. They say that enthusiasts have already managed to make their own payments, so as not to overpay for the ready.

Hifiman HM-901s

Among the electronic board of amplifiers there is a model with the prefix IEM – especially for the in-channel headphones. There is a balanced, high-voltage for high-impedance low-sensitivity headphones. There is a completely discrete circuit, without an operational amplifier (yellow board). There is a “musical”, with a changed character of the sound (black board at the top left). There is a universal, relatively inexpensive (lower left). In total, the number of PCB has already reached 7. When buying a player, it is necessary to clarify the equipment.

In our case, the player was equipped with an expensive Hifiman Minibox Gold card. It is based on two operational amplifiers OPA637SM and eight current buffers BUF634U. The metal casing OPA637SM operational amplifier is designed for the aviation and military industries, it provides temperature stability and protection against electromagnetic interference. That’s why the board is called Gold, unlike the previous usual red Minibox card. The board is universal, suitable for both low-impedance and high-impedance headphones.

Hifiman HM-901s

Passport characteristics of Hifiman Minibox Gold:

  • Output type: unbalanced
  • Frequency response: 5 Hz – 30 kHz
  • Maximum power: 440 mW
  • KG: 0.0003%
  • Channel separation: 104 dB
  • Signal / Noise: 110 dBA

All the parameters are very impressive! How impressive is the number of current buffers BUF 634U. As the manufacturer says, the power is equivalent to 15 smartphones iPhone 6s, working together!

Hifiman HM-901s

In addition to the boards, the discrete volume control with resistors is of interest, which gives the same loudness between the channels, whereas in variable resistors, the spread between the channels reaches several decibels at medium and low loudness.

Hifiman HM-901s

If the model 901 had only one headphone output (and a switch: balanced / conventional), now two separate connectors are made.

The balanced headphone output is made for connecting expensive models with your balanced cable. What gives such a connection? First, a very good separation of channels. Secondly, at the same nominal values ​​of the elements on the board, a double voltage can be realized twice. That is, balanced connection of headphones has quite tangible technical advantages. Of course, the amplifier must be of high quality, it can be a connection. It’s frightening to even imagine what kind of headphone amplifiers will start releasing cheap brand-names, if the balanced connection suddenly becomes massive.

Hifiman HM-901s

Filter mode is removed from the case, moved to the menu. By ear, there is no strong change in sound. To hear the difference from the inclusion of this filter is extremely difficult.

The high and low gain switch is also removed. All this is done to make the player more monolithic and stylish. On the faces left only two physical switches – those that are often used.

Hifiman HM-901s

The player menu is very simple. There is support for the Russian language, which is nice. In the latest firmware there are no special changes, the player remains brutal and ascetic.

The screen is quite faded compared to modern smartphone screens. This is done intentionally, to increase battery life.

Hifiman HM-901s
There is support for song covers. The files are simply poured onto the SD card, and then the player builds the library himself, analyzing the tags in the files.

There is a choice of all tracks, as well as filtering by artist, album, etc. Through a separate adapter you can give a signal to the digital input of the player. The digital input allows you to use the player as a pure DAC.
USB sound card mode is not supported, when you connect to a computer, the player becomes only a card reader.

Testing Hifiman HM-901s in RightMark Audio Analyzer

Uneven frequency response (in the range 40 Hz – 15 kHz), dB
+ 0,04, -0,71
Good
Noise level, dB (A)
– 102.1
Great
Dynamic range, dB (A)
102.1
Great
Harmonic distortion,%
0.012
Good
Harmonic distortion + noise, dB (A)
– 75.1
Medium
Intermodulation distortions + noise,%
0.015
Very good
Interconnection of channels, dB
– 98.6
Great
Intermodulation at 10 kHz,%
0.017
Very good
Overall rating
Very good

The figures of measurements approximately coincide with the passport data. Judging by the Internet, similar results were in testing the Hifiman HM-901. We conclude that the player has its own logic of the electronic part and is not optimized by the manufacturer for obtaining high measurement digits. Hifiman in his player does not focus on this.

Sound of Hifiman HM-901s

Ultrasone Jubilee Edition 25

We evaluated the sound quality on a number of headphones, including the Ultrasone Jubilee Edition 25 for $ 4,000 (limited batch for the company’s anniversary). Among the materials used – hand-processed precious ebony wood with a finish of silver of 925-th test, as well as ear pads from the skin of the Ethiopian long-haired sheep. Each model is collected manually in the foothills of the Bavarian Alps and assigned an individual serial number to emphasize its uniqueness. The mu-metal protective plate works to reduce electromagnetic radiation. The headphones have a sensitivity of 96 dB at 32 ohms, so they are shown a high-grade headphone amplifier, with a reserve in power and current.

The Hifiman HM-901 player sounds very good, for a portable device the sound is one of the best. Among desktop devices, you can find competitors, especially if there is no price limit, but among mobile players the player feels pretty confident. In the sound there is no special character, but if necessary, on the contrary, add some shade – the user can change the headscarf of the amplifier. Amplifier Hifiman Minibox Gold really liked. Pretty bright beautiful sound, without accent on HF. The bass in moderation, everything in its place, any headphones play music no worse than with a stationary amplifier. Is it possible to wish for an even better sound? Obviously, there are no limits to perfection, but for any slightest improvements one must be ready to pay.

Conclusions and feedback after use

During our detailed testing, we found out that the Hifiman HM-901s is an interesting and unusual audiophile player. It is very different from many other devices and is best suited for experienced experienced owners of portable players. HM-901s – the flagship of Hifiman players, and that says it all.

HM-901s is the flagship of Hifiman players

From the unprincipled moments we note that in the player of this price category we would like to see a better screen – for example, in the next generation. It would also be possible to think that along with a non-standard connector there was also Micro-USB, with the possibility of charging from external batteries during trips. I would like to think more about the case in the kit, for an expensive flagship model, this can make sense.

Video review of the player for true music lovers Hifiman HM-901



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