The Smooth Criminal?
PROS: Discrete resistor R-2R DAC, cheapest entry into the world of R2R DAPs, very natural analogue-ish warm sound presentation, bass note weight, excellently implement HiBy MSEB and Equaliser, classic retro user-interface, small/cute form factor, premium looking green and gold colour scheme with an excellent leather case that follow the same design language.
CONS: Not the most resolving DAP in its price segment, tiny screen, no WiFi or Bluetooth.
About HiBy.
Established in 2011 and based out of China, HiBy has extensive history of R&D, developing software and UI for other manufacturers, their own music player HiBy Music (which is a killer music player capable of doing things the average Android player can’t) and are now a major player in the hardware world too with a vast DAP lineup as well as earphones, IEMs, TWS, Bluetooth DAC/AMPs, etc.
Official Website – HiBy RS2 ($479)
Included in the box.
- HiBy RS2
- Type C to RCA digital coaxial cable
- USB Type C cable
- Darwin brooch
- RS2 green leather case
Tech Specs.
| Model | HiBy RS2 |
|---|---|
| Operating system | HiByOS PureAudio version |
| CPU | X1000E |
| DAC | Darwin Architecture |
| Audio format support | PCM384 / DSD256 |
| USB | USB 2.0 |
| Display size | 2.45” |
| Touchscreen | Yes |
| Resolution | 480*360 |
| Storage – card slot 1 | Micro SD card up to 2TB |
| Storage – card slot 2 | Micro SD card up to 2TB |
| Chassis material | Aluminium alloy |
| Dimensions | 90.3 *64.8*18.8 mm |
| Weight | Approx. 158g |
| Charging | 5V⎓1.5A |
| Battery size | 3500mAh |
| Charging time | Approx. 3h (0%-100%) |
Audio Specifications.
HiBy RS2 audio specifications (as tested within the 20Hz-20kHz range)
| Output port | 3.5mm PO @32Ω | 4.4mm PO @32Ω | 3.5mm LO @10K |
|---|---|---|---|
| Frequency response +/-1dB | 20Hz-20kHz | 20Hz-20kHz | 20Hz-20kHz |
| Output voltage | 2Vrms | 3.2Vrms | 2Vrms |
| Maximum output power | 125mW | 320mW | / |
| Rated output power (THD <1%) | 125mW | 225mW | / |
| Crosstalk rejection | 63dB | 82dB | 82dB |
| SNR | 118dB | 117dB | 116dB |
| Dynamic Range | 82 | 82 | / |
| THD+Noise | 0.006% | 0.006% | 0.006% |
| Output impedance | 0.47Ω | 0.94Ω | 10K |
Design and User Interface.
RS2 runs a customised PureAudio HiByOS, which as per HiBy is a targeted optimisation of system level audio processing, providing a clean, pure audio playback pathway and ensuring a purely audiophile music experience.
RS2 has a retro design language with tough bold edges, which is perfectly in line with the design scheme of HiBy’s family of DAPs. Its user interface has a green and gold theme and a simplified menu structure which is fairly intuitive and user-friendly to use. I actually quite like using the retro-ish UI of RS2 personally as it reminds of my childhood Apple iPod days but on the other hand, I can see the screen being cumbersome to use for people with big, fat or stubby fingers as it is than half the whole body in size, which is already compact to start with. Also, RS2 not having WiFi, BT or the capability to run streaming apps could be another problem for current users who completely rely on hi-res streaming from music services like Apple Music, Tidal, Qobuz, etc.
Main Interface – The main music library is classified under the following categories and you can use a combination of gestures and arrow keys to navigate the menu.
- All
- Files
- Albums
- Artists
- Genres
- Format
External buttons and outputs of RS2 –
- Top – 4.4mm BAL PO | 3.5mm PO | 3.5mm LO | Power Button
- Bottom – 2 Micro SD card slots and charging port
- Right – Volume wheel | LED indicator | Buttons for Previous, Play and Next
Some cool features of HiBy RS2.
MSEB – Whoever has tried the HiBy Music player has probably come across the MSEB EQ and knows how cool an EQ it is. It has layman terms as options to tweak, which takes the guess work of graphic equaliser away.
10-Band Graphic Equalizer – Nothing out of the ordinary here but I’d like to mention that being an audio engineer, I use such EQs on a daily basis and HiBy’s EQ works and reacts to gain increments and decrements very well. It’s a very musical sounding EQ!
Technology Inside.
Darwin Architecture – The Darwin audio architecture is HiBy’s in-house, all new hi-res audio processing architecture. Improving greatly upon traditional R2R technology, it incorporates a host of studio-grade functionality such as linearity compensation for the R2R network, adjustable FIR filter, harmonic controller, NOS/OS switch, etc. in a highly portable device. The flexible architecture is fully adjustable in-house, yielding infinite possibilities for evolution of this model and the next.
An output stage designed completely around R2R – Fully musical, realistic, natural and analogue, highly energetic when called for, fully immersive for the listener.
NOS / OS mode switch – NOS mode is non-oversampling. It bypasses FIR filter and oversampling for a more natural processing of the sound.
256-tap adjustable FIR filter – The Darwin architecture is capable of up to 16x oversampling, with a variety of AA filters suited to various design goals, e.g. phase linearity, high fidelity; also adaptable to the characteristics of different earphones.
Precision dual crystal oscillators, FPGA clock regeneration system – Dual precision crystal oscillators at 45.185MHz / 49.152MHz effectively reduce phase noise and jitter to -140dBc/Hz@1kHz offset.
Luxurious output stage circuitry – Utilizing current mode amplification, the output stage amplifies current via a OPA1652 and an LPF consisting of 2x OPA1612, offering high and clean input voltage and current to the output stage for exemplary transient and dynamic response. In conjuction with 2x flagship class OPA1622 amplifier chips, 4 independent channels of current mode headphone amplification and the professional digital volume controller NJW1195A, the circuit guarantees maximal fidelity of the output to the input, and maximal control over the headphone drivers.
MQA 8x unfolding – RS2 offers MQA 8x unfolding. It is fully authenticated, backward compatible and small enough to stream, so you can play MQA on any compatible device.
Format support – RS2 support all the main music encoding formats including PCM up to 384kHz / DSD hardware decoding at up to DSD256.
USB DAC / coaxial digital / Line Out all supported – RS2 can be used as a USB DAC (e.g. playing computer / smartphone audio). It can also output to other USB DACs (e.g. outputting audio from the RS2 to other USB DACs) and even output its audio as coaxial digital / line out signals.
Dual card storage – RS2 has 2 Micro SD card slots and supports storage of up to 4TB, with simultaneous usage of the two cards.
Battery Life – Up to 10 hours continuous play time. Standby for up to 40 days.
Uncharging mode–Independent battery operation as USB DAC – Press button to toggle charging in USB DAC mode–uncharging mode reduces battery consumption on smartphone and isolates device from external power supply noise.
Page 2 – Sound Analysis, Pair-ups, Comparisons and Conclusion.
Twister6 Reviews 
I would highly recommend you pair it up with a amp and use RS2 as the source. The headphone amp in such a small DAP is not good, but the DAC sections is almost a RS6. With a good portable amp, it bring the resolution to another level. I personally use it with Supermoon and HD800s with A100TB. Very good pairing
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Thanks, I’ll check out A100TB sometime. I can totally see RS2 being a good feeder source but you know, as a reviewer, I have to keep the articles simple and limited to reviewing the main product. IEM pair-ups are only used to further help describe the source sound with the IEM as a reference. I think forums like Head-fi with official threads are great places to further discuss customisation of rigs and combos. Otherwise, with all the portable amp options in the market, one can go crazy testing and writing pair-up impressions forever. It could be fun but then I have a massive backlog of other product reviews that I need to get to too! 😄 I’ll surely post my impressions in the RS2 Head-fi thread if I come across nice amps that pair really well with RS2. Cheers!
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