The Aurisonics Rockets utilize a dynamic "microdriver", a term that manufacturers occasionally apply to dynamic drivers smaller than about 7mm in diameter. The one in the Rockets is 5.1mm. The smallest such driver I've come across was a 3mm in the VSonic VC02.
I usually like in-ear earphones using small dynamic drivers, and the Rockets are no exception. Sonically, their greatest asset is the lack of any real weaknesses or shortcomings. Sounds cliché, but there aren't many earphones that make such excellent all-rounders—even with higher-end models there are usually more caveats when it comes to sound.
The Rockets deliver smooth and balanced audio. Compared to the best balanced armature IEMs I've tried in this price range, the Rockets are a little warmer, smoother, and more full-bodied, but not as crisp and clear. The bass is quite linear and very well-controlled, but still a little punchier compared to BA earphones with flat tuning.
In addition to having less punchy bass in comparison to the Rockets, those same BA earphones also can't match the Aurisonics' treble smoothness. While they don't have the absolute clarity of a top-tier BA earphone, the Rockets are refined, natural-sounding, and relatively forgiving. They sound neither thin enough to elicit complaints of being too "analytical", nor overly lush to the point of losing crispness.
While the treble is generally smooth, perhaps even a little laid-back, the Rockets' upper midrange is fairly forward, which helps with vocal clarity and prevents the tone from being dark. As a result, the Rockets don't sound dull even at lower volumes, though it's also worth noting that their sensitivity is at best average for an IEM.
Next to the Etymotic Research ER4 earphones from our Wall of Fame, the Rockets are more full-bodied and warmer in tone. The most noticeable advantage of the brighter ER4 is its clarity. The Rockets' bass is more impactful, however, and overall their sound is smoother and more forgiving.
Compared to the dynamic-driver VSonic GR07, the Rockets provide a smoother sound with less energetic treble. The GR07 is less forward in the midrange and has more pronounced bass and highs. It tends to be more sibilant, while the Rockets are quite smooth.
Philips' flagship in-ear, the Fidelio S2, is another strong dynamic-driver offering, delivering a crisper and more aggressive sound with brighter tone. Its bass is slightly boomier compared to the Rockets, but also more impactful. Vocals tend to be brighter on the Fidelio S2 while the Rockets sound more smooth, balanced, and relaxed.
The HiFiMan RE-400, also from our Wall of Fame, is perhaps the best spiritual match for the Rockets. Not only is the HiFiMan unit also based on a small dynamic driver, it too is a smooth, neutral earphone with prominent mids. The RE-400 is a little more crisp and boasts higher sensitivity than the Aurisonics. The Rockets have a slightly less midrange-focused sound, with a bit more bass emphasis and depth. Clarity is similar but the Rockets are less revealing of harshness and sibilance. Their soundstage is a little more spacious and natural compared to the RE-400.
Whereas normally I am happy with a great-sounding earphone that doesn't actively bother me when it comes to fit, design, or construction, the Aurisonics Rockets raise the bar pretty much across the board. In addition to superb sound quality and comfort, they provide tank-like build quality with water resistance and 5-year warranty, plus bonkers noise isolation.
What's not to like? Well, there is some cable noise (microphonics) carried by the heavy-duty cable when the earphones are used in the cable-down configuration and I couldn't make much use of some of the fit accessories. In addition, the compact, short-nozzle form factor of the Rockets and their reliance on a good seal to stay in place mean there will be a learning curve for 1st-time IEM users with these earphones. Nitpicks aside, however, the Rockets are simply fantastic. Up on the Wall of Fame they go!