Fit and Comfort

Seen above is the right channel of the DUNU SA6 MK2 placed into an artificial ear mold with the included white bore size M silicone ear tip installed. I have average-sized ears, and the ear mold above represents my own experiences well enough as a proxy. Size M silicone tips are my go-to for testing since foam tips are not included by some, and in this case I defaulted to the white bore tips because the S&S tips weren't comfortable for me in the long run and the candy tips were too soft and prone to breaking the seal. Tip rolling may well be a good idea here despite the various tips provided, but of course your mileage may vary. The same can be said about the shells too, especially with that indent at the top that was pointed out on the previous page. If that does not fit into your ears in the right place, the SA6 MK2 may not be a comfortable or secure fit. I suspect most people will be fine with it and I certainly had an excellent fit. Indeed, the more agressively contoured shells made for a semi-custom fit in my ears taking over the concha and ear canal smoothly. The nozzle is also not that large and inserts gently into the ear canals where the ear tips then do the job. The pre-formed ear hooks on the cable can also be hit or miss but here too the built-in angled cable connection helps alleviate the issue as seen in the image above. It ends up providing an extra support point for the IEMs which are already fairly light at ~6 g each, thus preventing physical fatigue. The single vent and the good fit achieved here resulted in a nice seal for me, which in turn means good passive noise cancellation too.

Audio Performance

Audio Hardware

The aforementioned vent is part of the acoustic engine on the DUNU SA6 MK2. This is because, despite it using six balanced armatures, the lower frequencies are handled by a Sonion AcuPass vented dual woofer, perhaps the 38D1XJ007Mi/8a. This venting is also taken advantage of by a tuning switch on the side which effectively helps with a different tonality from when the switch is off. The mids use two custom Knowles midrange balanced armature drivers and the higher frequencies are catered to by a custom Knowles dual tweeter driver. This results in a 2+2+2 3-way crossover in the SA6 MK2 and makes for a set of IEMs which is quite easy to drive courtesy an average rated impedance of 24 Ω (@1 kHz) and a relatively high rated sensitivity of 114 dB that I presume is 114 dB/mW—DUNU, please use correct units for your reported specifications! This means that the SA6 MK2 can be driven off any clean dongle, let alone a more powerful portable DAC/amp that you may already have if you are in the market for this set.

Frequency Measurement and Listening

I will mention that I have a general preference for a warm-neutral signature with a slightly elevated bass, smooth treble range, detailed mids, and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology begins with a calibrated IEC711 audio coupler/artificial ear that IEMs can feed into enough for decent isolation. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through a capable and transparent DAC/amp—I used the Questyle M15 here. I begin with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/12th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For IEMs, I am also using the appropriate ear mold fitted to the audio coupler for a separate test to compare how the IEMs fare when installed in a pinna geometry instead of just the audio coupler. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, especially those using a head and torso simulator (HATS). The raw dB numbers are also quite contingent on the set volume, gain levels, and sensitivity of the system. What is more useful information is how the left and right channels work across the rated frequency response in the DUNU SA6 MK2. The left channel was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the two channels are quite close to each other—within 1 dB to where it's acceptable in my books. I could slightly discern this now that I knew what to look for but I can't say I did notice this minimal channel imbalance prior to measurements being taken. Measurements taken after 25 hours of testing, which included these playing a mix of various songs as well as white or pink noise and sine sweeps, showed no difference. There was no perceived burn-in effect thus, and none was measurable, either. The response with the anthropomorphic pinna in place matched the ideal scenario in the coupler quite well well and this is an indicator of how good the fit and seal was when installed in the artificial ear. Please note that measurements taken after the coupler resonance matched here at 8 kHz are best taken with a grain of salt.


Here is the average frequency response for both channels of the DUNU SA6 MK2 plotted against my personal target taken from VSG.squig.link, which also gives you an idea of my personal preferences to better correlate any possible biases. The tuning of a set of headphones or earphones does not have to match my target as long as it is tuned with some direction, makes sense, and is executed well. After all, no one set will appeal to everyone, and having different options is what makes this hobby so interesting and hard to quantify. In addition, knowing the SA6 MK2 features a switch that enables two different tonalities, there's a second average frequency response here for these IEMs with the switch turned on—DUNU calls this "Atmospheric Immersion" compared to the "Default Signature" with the switch off. There's a small but perpectible difference between the two modes beyond just the obvious bass boost you see. The vented woofer drivers enable this option and I also noticed a slight change in the mids to where everything felt packed closer. So if the goal was to allow for a more concentrated flavor to be immersed in then sure, the switch and the name works. Personally I had some issues with the stock tonality to begin with and the switch being on mostly exacerbated things for me to where I mostly left it off as it ships out of the box.

I've listened to the original DUNU SA6 at a trade show once and have no experience with the SA6 Ultra, which I understand mostly adds some air courtesy increased treble extension to the SA6. The original set was a hit because it stepped away from the norm of neutral with bass boost while also having more relaxed upper mids to where it made for a great, non-fatiguing set for many people to jive to for hours. With the new SA6 MK2, DUNU seems to have gone further down the same road but I am not sure this works as well. I immediately noticed the SA6 MK2 was bassier and had recessed mids and vocals too. Indeed, we have an 8.5 dB bass shelf beginning from ~350 Hz with good extension all the way down to 20 Hz. There's not a lot of rumble or punch, however, to where those looking for it might be better off with a dynamic driver set. The mid-bass itself is clean, detailed, and fairly dynamic though so it hits all the notes I want well enough. Bass guitars have decent impact and the warmer tonality also worked well for classic rock music and drums alike.

Most male vocals come off well rendered and not recessed in case my previous statement resulted in second thoughts. I'd say the SA6 MK2 is also decent for general media consumption, but with the caveat of instruments taking precedence in the mids. Indeed, a lot of this I found came down to the early ear gain implemented here which is also shallower in practice to where female vocals didn't sound great at all and it also impacted timbre in a negative manner. DUNU went a bit too far here with shallow sounding harmonics too and the overall tonal balance is shifted greatly towards the lows. The consolation is it does make for another non-fatiguing set, especially with the lower treble continuing to be recessed compared even to the upper mids, but it also means string instruments and many percussion strikes/piano keys don't sound prominent. What I was hoping would be a great set for jazz and blues ended up not being so, and instead the SA6 MK2 comes off more suited for rock and country music. The treble extension was fine and the added air makes for an increased sense of clarity but ultimately there wasn't enough fundamental energy to take advantage of for orchestral music either.


The natural comparisons to make here would be with the DUNU SA6 and/or SA6 Ultra, both of which I have not tested enough to mention here. Purely from a pricing stand point, there are many IEMs which make this a highly competitive market segment. For example, there's the tribrid LETSHUOER EJ07M which arguably does the bass boost with relaxed mids presentation better. You get DD bass, forward-facing vocals throughout, and EST treble. The shells are also smaller and made of metal although I would say the SA6 MK2 can be more comfortable and looks great too. DUNU also gives you accessories on par with the very best in the business but overall I'd take the EJ07M for offering me a better version of this sound signature. With hybrids such as the XENNS TOP or even anything else that tries to go the Harman tuning route, things are not as simple. You have the potential to be hit or miss in both bass and upper mids alike with some going with a bass tuck that can hurt guitars and drums and many coming off slightly shouty with female vocals. The SA6 MK2 effectively becomes a decent alternative in this way, and more so if you are quite sensitive in the ear gain and lower treble region. I was fine with the execution on the XENNS TOP to where it's another set that I'd personally pick but I also know people who dislike it and are more likely to prefer the SA6 MK2 instead. Then there are IEMs such as the ThieAudio Oracle MKII which go the opposite direction as DUNU and offer a more emphasized lower treble, almost making it come off U-shaped and fatiguing/shouty/sibilant. Let's just say there's a reason I didn't even bother reviewing this set since it wasn't doing much to impress me. Listening to the Oracle MKII almost makes the SA6 MK2 feel like a masterpiece. But unfortunately the main takeaway here is it's hard to really recommend the SA6 MK2 based purely on its sound and it's not the easiest to make more amenable via EQ either.