Back when smartphone manufacturers began removing the headphone jack, many people, myself included, found it hard to accept. After all, phones have become one of our primary means of listening to music, and the DAC/AMP that comes with the smartphone left much to be desired.

When audio output functionality was separated from mobile phones and introduced as a standalone audio system that was put on the market, traditional HiFi brands suddenly had an epiphany - "We know how to do this!" And just quickly realized its potential and began developing portable HiFi devices

When USB headphone DAC/AMP hit the fast lane of traditional portable HiFi, there was no turning back.

Various traditional HiFi technologies have been widely applied to dongle, and the sound quality of many headphone dongles has not only surpassed their predecessors but has also surprised even the most avid audiophiles accustomed to professional players.

To see how much breakthroughs and progress USB DAC/AMP can achieve in terms of sound quality, let's take a look at the decoding earphone amplifier integrated gear, the Hiby FC6, from Hiby Music.

The HiBy FC6 is built upon HiBy Music's latest professional player products, sharing the same hardware and software features such as the DARWIN architecture, FIR filter, R2R technology, and NOS/OS modes, which reflects HiBy Music's breakthrough and expertise in DARWIN architecture in recent years. The DARWIN architecture was previously only applied in the professional player field, but the HiBy FC6 is the first to bring this architecture to a dongle USB DAC/AMP. This suggests that the DARWIN architecture will continue to evolve and expand into broader audio fields in the future.

HiBy FC6 is equipped with professional player-level hardware, the FPGA reclocking system and dual independent OPA1622 headphone amplifier chips. Furthermore, the HiBy FC6 supports MQA 8X unfolding and can reproduce high-quality audio up to PCM768kHz/32Bit and DSD512, allowing for maximum fidelity in music playback.

The HiBy FC6 portable DAC has a color display screen and a color indicator light that show its working status and playback parameters. It also has physical volume keys and mode keys for easy operation. It should be noted that unlike many high-end portable headphone DAC/AMPs on the market, the FC6 only has a 3.5mm single-ended headphone jack and no balanced headphone output, which may be inconvenient for some users.

Also, the two stock cables that come with the HiBy FC6 have black rubber insulation and are relatively stiff, which affects their appearance and may impact their usability to some extent.

The HiBy FC6 utilizes R2R decoding technology, which is not commonly found in portable headphone dongles. This technology has recently been adapted from desktop and player audio systems and integrated into the USB headphone DAC/AMP market. It's worth mentioning that the HiBy FC6 features the Hiby Music DARWIN-HDR function, which enhances dynamic performance and enriches three-frequency details through audio processing algorithms, similar in principle to HDR in photography.

In terms of analytical ability, I find that the HiBy FC6 delivers a relatively complete and accurate representation of sound information, even in complex music genres. In my opinion, the HiBy FC6 meets the requirements of a dongle with its level of detail and resolution. Although the imaging in the soundstage may not be very sharp, it delivers a natural and comfortable rendering of instrumental and vocal timbres that's enjoyable to listen to.

HiBy FC6 dongle got excellent imaging and instrument separation performance, providing an immersive listening experience across most music genres. While it may not match the soundstage of a professional player, it's will be a great choice for listening to music with large ensembles, as it provides a good sense of the atmosphere and the interplay between the different musical elements. The FC6's dynamic control is well-executed, with a focus on stability and resilience that preserves the integrity of the musicality while providing a satisfying amount of power.

In terms of tonal balance, the HiBy FC6 leans towards a warm and balanced sound signature. Its emphasis on the midrange over the high and low frequencies avoids the "pleasing" tone that many headphone dongle DAC/AMPs strive for. The HiBy FC6 presents a complete and authentic sound experience by prioritizing the full range of sound. The frequency distribution is also accurate and authentic, without artificial enhancement of the high-frequency range. Therefore, the HiBy FC6 is versatile and compatible with a wide range of music genres, from the high frequencies of string instruments to the low frequencies of the drums.

When it comes to classical music, let's take "The Blue Danube" as an example. Paired with the Mojito headphones, the HiBy FC6 delivers a beautiful picture composed of musical notes. In the first half of the piece, the interweaving performance of the violin and flute captures the transparent, water-like texture and the flowing light and shadow that are brought forth by the high frequencies of the Hiby FC6. The unexpected triangle adds to the experience, appearing like a bright light floating on the water's surface, disappearing in an instant but leaving a lingering light. As the song progresses to the middle, the addition of the cello and double bass brings the music's atmosphere together, transporting us to a splendidly lit palace where numerous men and women are singing and dancing.

For pop vocals, let's test The Beatles' "Yesterday". We paired the FC6 with Hiby Music's in-ear monitor Crystal 4. I feel that the HiBy FC6 significantly enhances the sound quality of this single dynamic earphone, making it more lively and warm, from the guitar in the prelude to McCartney's vocal details. The moderate relaxation and subtle graininess make the vocals more lifelike, even bringing a bit of vocal resonance and making the emotions of the song feel more genuine and natural.

It can be said that as a R2R dongle headphone DAC/AMP, the HIBY FC6's audio performance is beyond doubt and very satisfying. Hence, we can further evaluate it with a more demanding standard. If we compare the FC6's audio quality with that of professional players of similar level and price, I believe it has reached or approached similar levels in the following aspects:

Integrity of sound

USB DAC/AMPs are often designed and tuned to just meet basic needs, lacking the balance and completeness that a true HiFi device requires. However, the FC6 fully presents the sound in its original form, avoiding shortcuts in the design process, and exhibiting the pure style and taste desired by HIBY Music. Therefore, in terms of musical variety and sound authenticity, the FC6 can rival similar professional players.

Purity

Generally, improving the purity of USB DAC/AMP products is kind of challenging due to the limitations of size and power supply. However, as a portable audio device mainly used for the on-the-go, this issue is often not apparent. The FC6 is exceptionally pure, even comparable to professional players in the same category, as we can distinctly perceive the sense of space and deep tones of the sound background. In terms of audio purity, the FC6 is a breakthrough among dongles and USB DAC/AMPs.

Density and power

The FC6 presents exceptional density and stability, with a robust and steady sound that is closer to that of a player DAP than a traditional dongle. Even in terms of detail expression, the FC6 impresses us with its impactful sound.

Listenability

In general, many headphone dongles perform well in listenability. However, thanks to the R2R decoding and the DARWIN architecture, the FC6's sound is gentle, relaxed, and highly listenable, even surpassing some professional music players.

If we raise the bar and set a more stringent standard, we may find that the HIBY FC6 dongle has some differences when compared to other players in the same category and price range:

The compact size and limited power of USB headphone DAC/AMPs always pose a challenge for achieving an optimal soundstage, dynamics, and drivability. Some manufacturers resort to aggressive tuning and design to cover up these shortcomings. However, the FC6 takes a more conservative approach by prioritizing stability and control over the sound, which I personally appreciate. However, compared to professional players, the FC6's performance in some music styles may be limited, and it may not be able to drive some headphones as effectively.

The HiBy FC6's performance in complex music genres may be slightly direct and not as capable of highlighting the nuances in tonality and levels as professional players can.

Another area that I believe could be improved is the extension of the high and low frequencies. While the HiBy FC6's high and low frequencies within the frequency range have excellent volume and shape, they appear to come to an abrupt halt at a certain point without a gradual tapering, which results in a slight deficiency.

These "gaps," as I call them, are mainly in comparison to professional players in the same price range or higher, such as the HIBY R5II. If we evaluate the HiBy FC6 based on the requirements of a portable USB headphone DAC/AMP, it would undoubtedly meet or even exceed our expectations. The sound quality of the HiBy FC6 DAC is way more impressive for a dongle.

Actually, my phone does have a 3.5mm headphone jack. However, when I listen to music on my phone, I still prefer to pair it with a dongle.

A few years ago, I could never have imagined that USB DAC would achieve such a high level of audio quality as they do now. And today, I can only wonder how much further they will develop in the future.

The HiBy FC6 R2R DAC/AMP with Darwin Architecture has given me inspiration that this transformation of dongles from a necessary accessory to a high-end HiFi audio device is not only due to the application of new technologies, but also represents a shift in the category of audio devices towards a more experiential and enjoyable listening experience. This evolution has provided us, as users and audiophiles, with more choices and ways to appreciate music.