DUNU SA6 Ultra Review - You may want it, but you can't have it

DUNU SA6 Ultra Review -

Photography by Chitoh Yung (@chitohgraphy)


The first reviewer-collaboration IEM was the Crinacle x Fearless Dawn, released just two years ago in March of 2020. Since then, the market has seen an explosion of these IEMs, with popular reviewers teaming up with manufacturers to release IEMs that capture renditions of their ideal sound. The SA6 Ultra, then, is a collaboration between DUNU and YouTube reviewer Zeos. It maintains the 6BA driver configuration of the SA6 with a small increase in price to $580 USD. As always, there is one burning question on my mind: Does the SA6 Ultra do its excellent predecessor justice, or does it fall prey to the all-too-common “not really an upgrade, just different or worse” upgrade cycle?

This unit was provided for review by HiFiGo. As always, what follows are my honest thoughts and opinions to the best of my ability.

Source & Drivability

All critical listening was done off of an iBasso DX300 and iPhone 13 Mini with the stock accessories. I used the silicone ear tips in lieu of the included foam tips. Silicone ear tips are generally optimal unless isolation is a consideration. They don’t require as much maintenance, they don’t attenuate high frequencies, and they will last much longer. The SA6 Ultra takes minimal power to drive and I had no issue hitting my usual listening volumes of ~70dB. Hissing was not an issue. If you'd like to learn more about my listening methodology, test tracks, and general beliefs in audio, then I would encourage you to check out this page.


  • Leather carry case
  • Silicone ear tips s/m/l
  • Dekoni Bulletz Foam tips s/m/l
  • Cleaning tool & microfiber cloth
  • DUNU Hulk Mini cable 0.78mm w/ swappable 2.5/3.5/4.4mm terminations

The case that comes with the SA6 Ultra is DUNU’s classic leather case in dark blue. This is a high-quality case; in fact, it’s one of my favorites due to the slick form factor and the addition of a mesh slot inside for accessories. The case is certainly not bombproof like a Pelican case, but it has a decent rigidness to its structure.

The SA6 Ultra’s cable, the Hulk Pro Mini, is an improvement from the original SA6’s but it doesn’t compare to the lofty heights of my favorite (and now discontinued) DUNU cable, the DUW02. Personally, I found the Hulk Pro Mini to be somewhat microphonic and not quite as supple. The excellent build quality is still there, though, and this cable also features DUNU’s legendary swappable terminations. Unlike some other mechanisms that rely solely on friction to swap between terminations, DUNU’s cables have a patented locking mechanism. It’s a pleasure using this feature and knowing that your IEM is ready to take on most any portable source.

The SA6 Ultra has all the hallmarks of the original SA6’s fantastic construction. It utilizes stabilized wood faceplates juxtaposed with smoky gray resin for the shell. A peek at the internals reveals extremely clean wiring between the balanced armatures. Finally, a switch toggle resides in the back of the shell to select between two levels of bass. Unlike some other IEMs which use switches, the SA6 Ultra’s switches have enough purchase to be adjusted with the use of a fingernail. Simultaneously, they do not protrude to cause undue discomfort; indeed, I found the comfort of the SA6 Ultra to be excellent in my small-medium-size ears. Of course, be aware that fit and comfort will vary from one listener to another.

Sound Analysis

There are a number of tuning philosophies in the IEM world. However, the most prevalent is the style of tuning that many Chi-Fi IEMs have rode to success: Harman. It’s not difficult to see why, given that the Harman target is backed by solid research, offering majority listener appeal to IEM companies on a platter. But before this style of tuning was popularized, many of the best IEMs were tuned with more…artistic liberties in mind. By “best IEMs,” I think of IEM reviewer Crinacle’s infamous IEM ranking list, a list that I found myself glued to in my early days of the hobby, and its elusive S-tier IEMs: the 64 Audio U12t, qdc Anole VX, Sony IER-Z1R, and the Vision Ears VE8. Not a single one of these IEMs adheres to the modern tuning orthodoxy and perhaps for good reason.

The frequency response below was measured off a clone IEC-711 coupler. Measurements after 8kHz should not be considered entirely accurate due to the presence of a resonance peak. If you would like to compare the Studio 4 to hundreds of other IEMs I have measured, then please follow this link.

In any case, the original SA6 might be considered one of DUNU’s best IEMs, inspired by the aforementioned qdc Anole VX. So what is the SA6 Ultra? The cliff-notes version is that it is a slightly refined SA6. It has - again, I use this word - slightly better tuning with comparable technical performance. The tuning of the SA6 Ultra can be adjusted between Atmospheric and Normal modes; it would be best to just think of Atmospheric mode as being a minor bass boost (by about 2dB) that lends to a slightly warmer presentation. This is my preferred setting. Either way, the SA6 Ultra’s bass is relatively clean and even has some meat behind its BA woofers due to the strong focus on sub-bass.

But the real meat of the SA6 Ultra’s appeal lies in its midrange. Whereas most conventionally tuned IEMs begin rising at 1kHz, peak at 3kHz, and then slope off in a similar fashion, the SA6 Ultra has a relatively low rise to 3kHz and stays mostly linear from 1.5-4kHz. This lends vocals a soulfulness, pushing them further back in the mix. Harshness, or sibilance, is mitigated even further by an abrupt recession from 4-6kHz in the lower treble. This allows the SA6 Ultra to put a moderate emphasis on sparkle without compromising instrument timbre. Worth noting: a criticism I had of the original SA6 was its lack of energy past 10kHz which lent to a more closed-in presentation. The SA6 Ultra’s upper-treble extension is slightly better.

Technical Performance

Like its predecessor, the SA6 Ultra would not win awards for its sheer resolution. Notes have a slightly soft edge to their attack and a mostly smooth taper to decay. These characteristics can be predicated on the SA6 Ultra’s reserved pinna compensation and its safe treble response. However, it’s worth noting that many balanced armature IEMs suffer from a plasticky-ness to their timbre (often due to poor bass and treble extension). This isn’t the case with the SA6 Ultra which has remarkably good timbre for a BA IEM. Another quality that initially struck me about the SA6 Ultra is its coherency. It simply sounds fluid, as if there are no gaps or jarring characteristics to the way it presents music. In conjunction with its extremely smooth tuning, the SA6 Ultra’s imaging is above-average. It’s not the most open-sounding IEM; however, it’s quite easy to localize instruments on the soundstage. Overall, the SA6 Ultra sports comparable technical performance to the SA6: good, but not great.


While the original SA6 might have been compared to legendary IEMs as a “mini qdc Anole VX” or “mini 64A U12t”, I’ve always thought it straddled a line somewhere between the two. This line gets even blurrier with the SA6 Ultra. It definitely doesn’t have the sheer resolution of the qdc Anole VX, but the SA6 Ultra’s tuning is more enjoyable and it does not have the notorious timbre issues of the VX either. I like to think of it as simply being a very well-tuned set that most listeners, especially the most critical ones like myself, would struggle to find fault with.

Outside of flagship IEM comparisons, the SA6 Ultra enters a competitive landscape with established players like the Moondrop Variations and Symphonium Meteor. But I think it has what it takes to distinguish itself given that it offers a flavor of sound that these other IEMs are not targeting. The Variations almost perfectly falls into the bucket of tuning (read: Harman) that I wrote about earlier. It should appeal to listeners who want a high-clarity sound that prioritizes technicalities while being balanced. On the other hand, the Meteor is all about fun, from its enormous bass and sparkly, boosted upper-treble response. The SA6 Ultra falls somewhere in-between these two tunings with commensurate technical performance.

The Bottom Line

The original SA6 was a good, even great, recommendation at its ~$500 MSRP. It hit a sweet spot for listeners who wanted a taste of unorthodox, flagship-level tuning without the accompanying price tag. The market has become more competitive since the original SA6’s release, but it should come as no surprise that I share similar sentiments about the SA6 Ultra, upping the ante accordingly.

But don’t pull out your wallet for this IEM just yet; in fact, you might not even be able to! The SA6 Ultra was a limited edition release that’s since sold out, and if you’re looking for an alternative, you might be suited by the SA6 MKII instead. Stay tuned for my thoughts on the SA6 MKII!

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