Review: HiBy RS2 – R2R To Go

User interface and software

RS2 debuts what HiBy calls its HiByOS PureAudio version. For those who don’t know the company, HiBy started out primarily as a software developer, creating music player operating systems for sister company Cayin and others. HiByOS has evolved over time to include a variety of different features for different DAP platforms, but this is the first time it’s been used for an RS-series Darwin DAP. 

The HiByOS interface for RS2 carries over the green and gold Darwin colourway with six active functional blocks on the ‘home page’, long with a status bar up top for displaying the time, volume, input/output and battery level. Each of the blocks is clearly labelled with its own icon: Music, Darwin, MSEB, Play, System and About:

Music. This is the first and most obvious function, giving you direct access to music stored on mSD cards and/or removable USB storage. You can view your music in six different ways: 

  • All: individual tracks on all sources. 
  • Files: a directory tree view per storage location. 
  • Albums: when selected, you have the option of manually or automatically scanning one or more sources for music files, which are then collated as albums based on tags.
  • Artists: as with albums, only listed by Artist tag. 
  • Genres: as with Albums and Artist, only listed by Genres tag.
  • Format: select catalogued files by file format. 

Selecting a track from any of these blocks fires up the HiBy Music Player interface and begins playback. You can then move backward or forward based on the view you’re currently in. The only option I’m missing is Album Artist, since all my files are tagged by Album Artist rather than track artist.

Darwin. This block lets you choose from three Darwin-specific options: Digital Filter, NOS and Harmonic Controller. HiBy gives you a choice of 10 different digital filters, all of which very subtly affect playback. I personally don’t hear much variation between filters, so you’d have to listen for yourself to see if you can, and if so, which one sounds best to you. 

NOS (non-oversampling) is a native R2R setting that presents sound differently, avoiding so-called ‘ringing’ artefacts sometimes introduced by oversampling music files during digital conversion. Again, test for yourself to see which mode you prefer.

Lastly, the Harmonic Controller is another way of fine-tuning the frequency response of the digital conversion. Depending on the IEM or headphone you use, setting this slider will help you tweak the sound to your liking.

MSEB. Originally dubbed Mage Sound 8-Ball, MSEB is HiBy’s systemwide DSP filter that lets you equalise sound to your liking. Unlike traditional equalisers, MSEB uses sliders you can change based on easy-to-understand audio descriptions, such as Overall Temperature, Bass Extension, Note Thickness and Sibilance. In my experience MSEB is less aggressive than many EQ options on other DAPs, and also very effective in doing exactly what it describes. Moving the high frequency sibilance slider towards ‘soft’ audibly affects the frequencies associated with female vocal sibilance, for example. This makes MSEB a very useful tool for ‘fixing’ slight imperfections in the music or your playback gear, or tuning playback to taste. 

HiBy has included some of the recent additions to its MSEB software here, including downloadable filters for specific IEMs, the ability to choose the adjustment range from fine (-20 to +20) to excessive (-100 to +100), and the ability to save and load your own preset settings. 

Play. This block gives you access to numerous software playback settings, including:

  • Equalizer: a traditional 6-band graphic equalizer with eight presets and a custom setting you can save and load.
  • Update database: use this to re-scan your sources for new music files.
  • Music update mode: select how to scan for new music, automatically or manually, and enable auto detection of MQA files.
  • Play mode: lets you choose between playing back playlists, looping, shuffling or looping playlists.
  • DSD output mode: select between native, DoP or PCM conversion for DSD files.
  • DSD gain compensation: select your DSD dB compensation, from 0dB to 6dB.
  • Resume play from last: choose if you’d like playback to resume from your last position, last track, or none.
  • Gapless playback: enable seamless playback of gapless albums.
  • Maximum digital volume output: sets a fixed maximum volume on USB/COAX output. 
  • Max volume: choose your maximum volume level, from 0 to 100, useful for preventing accidentally high-volume output with sensitive IEMs.
  • Power on volume: lets you choose between last volume setting and any setting from 0 to 100 on powering up the player.
  • Crossfade: enables crossfade effect between tracks.
  • Gain: sets a higher gain setting for harder to drive IEMs.
  • ReplayGain: lets you normalise the volume for replaygain-tagged files. 
  • Balance: adjust volume balance between left and right channels during playback.
  • Play through folders: let’s you continue playback from one folder to the next automatically, otherwise playback stops at the end of a folder.
  • Play through albums: as above, lets you play through albums, or playback stops after the current album is finished.

System. This block gives you access to a number of software and hardware-level options, including:

  • Language: choose and change your UI language. Usually set at startup.
  • Brightness: I’ve set mine to 50%. It’s a bright and crisp screen.
  • Backlight time: cuts off backlight to save battery power.
  • Theme color: change your font and background colours to anything you like.
  • Font size: makes it easier to read the tiny text on the tiny screen.
  • USB mode: set USB mode to storage (for external drives) or DAC (for using as a DAC with your smart device).
  • Button activation when sreen… (is off, I assume): enable/disable button use while screen is off.
  • Time setting: a curious one for a DAP, you can set the time and date, which is displayed on screen.
  • Idle timer: set time to idle power.
  • Sleep timer: set time to power down. 
  • Battery percentage display: important if you’re particular about battery power remaining.
  • Standby: can set RS2 to standby rather than sleep. 
  • Status LED: disable/enable the LED status light.
  • Screensaver setting: lets you choose between two types of screensaver.
  • Screen rotation: flip the screen 180 degrees to use it with ports at the bottom or top. 
  • Restore factory settings: restore to the last clean FW update, and can also reset music database.
  • Firmware update: since there’s no WiFi, you need to load new firmware to an SD card and update from here. Pity you can’t update firmware off an external USB device too.

Normally this type of ‘barebones’ OS would be fairly limited in its functionality, but as you can see above, HiBy have added numerous personalisation options that make RS2 more versatile. 

About. This box displays a screen showing the storage capacity of installed cards (though not of external USB devices), along with firmware revision, serial number, and other useful information for getting additional support from HiBy.

Continue to Hardware specs



Guy Lerner

Guy Lerner

An avid photographer and writer 'in real life', Guy's passion for music and technology created the perfect storm for his love of portable audio. When he's not playing with the latest and greatest head-fi gear, he prefers to spend time away from the hobby with his two (almost) grown kids and wife in the breathtaking city of Cape Town, and traveling around his native South Africa.


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