Hiby FC3 ($69): The FC3 is a slightly smaller device but has similar usability overall. It does have internal volume control which gives it a slight edge with sensitive IEMs, but the S9 Pro has a slightly cleaner noise floor and a lot more power for less sensitive gear making it the more versatile source altogether. In terms of the tonality, the S9 Pro is slightly brighter and more revealing around the treble especially, while the FC3 represents a more linear sound overall. That said, under scrutiny, the S9 Pro is a substantially more impressive source as you’d expect given the large price gap – but the difference in performance grows small with more efficient IEMs. Immediately, its bass is deeper extending and more dynamics, delivering greater rumble and power.
The FC3 is just a touch warmer here but less nuanced and robust altogether. Its midrange is slightly more even, that said, and it does have a slightly more neutral and defined note presentation. The S9 Pro stretches wider, its layers being far more delineated, but its foreground is not quite as textured due to its denser voicing. The S9 Pro has a more energetic treble, and it has a little more bite to its transients, giving it the advantage on detail retrieval. The S9 Pro especially has a much larger soundstage which cements it as the superior source although the FC3 nails tonality at a much lower price.
Astell & Kern Dual DAC ($149): The Dual DAC is a smoother and more refined sounding source with a greater focus on tonality and staging. It too is dead silent but also with lower output power and a slightly higher 2-ohm output impedance, plus a lack of balanced output. It makes up for this with class-leading build quality and some unique sonic characteristics. Bass is more dynamics and powerful on the S9 Pro as one may expect. The Dual DAC has less authority but does have a slightly more articulate and controlled mid-bass in return. The midrange is slightly more even-handed on the Dual DAC, both are smooth and dense. I did find the Dual DAC to discern textural nuances slightly better here than the S9 Pro but the two are very similar overall.
This same trend continues to the treble, the Dual DAC has a little more bite to its lower-treble and more texture here, it also has a cleaner background and matches the S9 Pro for extension. The S9 Pro has more energy, its presentation is more vibrant and airy. Staging wise, the two also trade blows, the Dual DAC has a more rounded stage with noticeably more depth, making it slightly more immersive. The S9 Pro has a wider stage with slightly better layering and a more focused foreground. Still, as much as I want to love the Dual DAC, you do pay for the refinement in the form of a higher output impedance, fixed cable and lack of balanced IO.
Earmen Sparrow ($199): A closer competitor with balanced output and focus on high output power (current unspecified). The Sparrow is a slightly higher contrast source, still showcasing strong balance but is more coloured than the S9 Pro. Despite its size, it matches the S9 impressively well on output power but at the cost of being less shielded from EMI drying my testing. The S9 Pro has slight edge on bass weight and extension, rumble is slightly more defined and powerful. The Sparrow gets close and it has a lick of deep-bass emphasis which gives it a slighty bolder note presentation. The Sparrow has a higher contrast midrange with a leaner note weight.
It resolves slightly better, its notes being slightly more defined and separation being slightly better. The S9 Pro meanwhile has better layering and a slightly more accurate timbre. The Sparrow has a little more bite in its lower-treble, giving it an edge on fine detail retrieval. Meanwhile, the S9 Pro has more air and headroom, and it’s background is more stable and defined. This plays most into its soundstage performance, though the Sparrow is actually wider, this comes at the cost of a diffuse centre image, the S9 Pro being noticeably more organised and stable. The Sparrow will appeal to those wanting a more engaging tonality and the widest soundstage.
The biggest accolade I can award the S9 Pro is mostly contextual but still speaks well for Hidizs creation. Mostly, many dongles do little that calls for complaint but similarly, little to differentiate themselves. The S9 Pro does, however, and in numerous categories. It manages to sound much bigger than you’d expect from a portable source, both with regards to dynamics and soundstage expansion. While some match it, few are as well-rounded. The S9 Pro nails the fundamentals being convenient to use whilst boasting a black noise floor, linear FR and sub 1-ohm output impedance. Balanced connectivity and well above average driving power are nice to haves that do enhance versatility and better justify its more premium pricing. This is not suited for those wanting a smooth or warm sound and is lacking volume control granularity for sensitive IEMs. Overall, the S9 Pro is versatile, nicely resolving and a strong overall package that I can highly recommend.
The S9 Pro is available from HiFiGO and Amazon (International) for $119 USD at the time of writing. I am not affiliated with Hidizs, Amazon or HiFiGO and receive no earnings from purchases through this link.