Disclaimer: The Mk4 was provided by Kinboofi for the purposes of this review. I have no financial interest in Kinboofi, nor are the words here influenced by any entity or person other than myself and the several voices that roam freely inside my head.
I have to say, the packaging did not set the stage for what I found inside. The black lift-top pressboard box reveals a small clamshell soft case surrounded by foam. Both the packaging and the soft case are on par with what ships with many $25-50 earphones these days. On top of that, all of the kit was fitted (polite word for crammed) into that small case, 6 sets of tips, the cable, and both earpieces along with a small tool for adjusting the switches. The upside is the earpieces were bagged individually to protect them from scratching and even as I got the cable out of its bag I was impressed by how supple it was. This is a case of the packaging doing a less than great job of advertising for what is inside.
Here we turn the corner, the build quality of the Mk4 is absolutely first rate. The transparent light blue inner shell makes it easy to see the internals while the brass nozzles have a pronounced lip for holding tips firmly in place. The faceplates are a darker blue than the feature picture would make you think as it was backlit and allowed more light through than typical. The gold rim and logo are tasteful and the seam between the shell and faceplate is neither easily visible or felt. The fact these are hand-made and not machine produced is obvious in the attention to detail. The switches at the rear cannot be felt when running a finger over the shell and require the provided tool to adjust. Feedback from the switches is positive with a very satisfying click in either the on or off positions. The mmcx connectors are equally well fitted with no gaps or ridges to be found. (The connectors are extremely tight which is probably a good thing for the longevity of the mk4 but will require a bit of extra effort early on). The shells are medium sized in height and width with slightly greater than average depth. Nozzles exit the lead edge of the earpieces at the highest point which allows the body of the earpiece to rest below the ear-canal for a comfortable fit. I had no comfort issues with the Mk4 wh
en wearing them for extended periods at the office.
The Mk4 has 4 balanced aramature drivers which Kinboofi advertises as being 50% knowles and 50% Bellsing. The labels that can be seen through the shell are a knowles 22955 and 29689 along with a Bellsing 30095. I was not able to see the 4th label to confirm its part #. Nominal impedcance is listed as 22Ω with a sensitivity of 116dB/mW and the Mk4 shows it by being very easy to drive from a cell phone or tablet. I found the Cayin N3 with its lower than average output was still easily able to drive the Mk4 to levels above that which I feel comfortable listening even when set on low gain.
One of the first things I noticed while un-boxing the mk4 was the cable. The provided cable is a 6 wire silver-plated copper that is extremely supple and pliable. A straight 3.5 mm jack with a knurled metal housing has a stepped strain relief which the 6 wire braid exits as it runs to the splitter which is also a brushed aluminum fitting, two 3 wire braids exit the splitter and carry to the pre-formed earhooks and mmcx connectors. I am particularly impressed with how good the earhooks look. I know this is a small thing, but most earhooks look bulky and detract from the overall aesthetic. The Mk4 on the other hand does not look like it has earhooks. Part of the reason for this is the clear lightweight material used, and part is the earhook is longer than most so when worn the end of the earhook is below the ear where it will not rub or cause fit issues. The mmcx connectors themselves are gold plated for better contact and housed in a fairly standard brushed aluminum casing with a red ring at the base clearly indicating the right wire. Earpieces are not marked R/L but only fit one way so it really isn’t necessary.
I did find the sound somewhat tip dependant and found the best sound was provided by larger bore tips than those provided. Both sets of provided tips limited the bass more than I would prefer and I ended up using whirlwinds for most of my review listening.
In a single word, the bass on the Mk4 is best described as accurate. It is not elevated and won’t please the basshead crowd, but for those looking for clear, crisp, detailed bass, the Mk4 does a good job of it. Attack and decay have good speed leaving little or no slur to bass runs and allowing the mk4 to produce more details in the mid-bass than common at its price point. Sub-bass is present as well, but can fool you as it isn’t pushed forward and does not appear unless the track calls for it. Some will call the Mk4 overly bright as many today have a skewed sense of neutrality where bass is presented at well above neutral levels.
Mids flow nicely from the mid-bass with a clean transition and a very natural tone. Detail levels are on par with the iBasso IT04 and Eartech Quint and easily surpassing other recently reviewed models in its price range like the Brainwavz b400, Fiio FH5 and LZ A5. Vocals are full and smooth with good timbre and weight. I didn’t find any of the vocals particularly lifted in front of others, nor did I find any vocal range particularly recessed or lacking. I was also particularly impressed with the Mk4’s rendering of acoustic guitar as it gave a more natural tone and weight to Gordon Lightfoot than I have heard in most in-ears. Overall, this is the single stongest point of the Mk4 and for those who enjoy mid-centric in-ears (like me) this one should be on your short list.
Lower treble is slightly forward with switches in their default position but has a step down around 7kHz and a steeper roll-off above 11kHz that gives it plenty of air and sparkle without feeling overly strident of fatiguing. I was particularly impressed with snare and cymbal which both have a very lifelike presentation. I find that most iems that try and minimize fatigue also round off all the sharp edges which takes away from the reproduction of snare as it should have a sharp attack. For those that are somewhat more treble sensitive, the switches give the option to take it down a notch without it being the huge steps typically seen in tuning switches.
The good thing is the switches on the Mk4 don’t try to drastically alter the signature, they mildly elevate one end of the spectrum or the other. Switch 1 focuses on the upper mids and lower treble and is a slight push forward when on. Switch 2 focuses at the low end of the spectrum and again when in the on position provides about a 5% increase in sub-bass and lower mid-bass (<200Hz). I am personally a fan of the Mk4 with both switches in the down position but will also say there are times that bit of extra life flipping both switches to up brings are welcomed. If you find tracks fatiguing switching #1 down will almost certainly help reduce that fatigue without going far enough to feel closed in or lacking in air. Some may lament the lack of a larger shift in signature but instead I am going to applaud it as it changes the sound without making one setting notably more musical and better than the others. Too often you can tell which switch position the manufacturer intended you to use as the others are less than acceptable.
Soundstage / Imaging:
Soundstage is large with slightly bigger width than depth but with good overall dimensions and even a good sense of height. When listening to orchestral pieces it was easy to seat the orchestra with good instrument separation. I found no tendency to get muddy or lose that separation as tracks got more complex and layering stayed very clean even with the busiest tracks I had on hand. Spatial cues were well rendered with movements being easily audible. I particularly enjoyed the Cowboy Junkies – So lonesome I could cry off the Trinity Session as it highlighted her movement on stage and the cavernous echoes of the cathedral.
The $200 range has become one of the hot-spots of recent releases so I have tried to compare the mK4 to some other fan favorites at nearly the same price point.
To me, this is the the Mk4’s biggest competition as the Kanas Pro does an awful lot very well. The good news is the Mk4 manages to stay on the same plane with it most of the time. I do think the low end extension is a bit better on the Kanas pro and details in the bass are about a dead heat so neither pulls away there. Mids are equally good on both with a slight edge to the Mk4 on detail level and texture. Lower treble I think the Kanas pro is a bit more lively and can make vocals a bit more intimate while the mk4 is a bit more reserved and less prone to causing fatigue. Overall, this one comes down to preference as both are good and similar in some regards. Those who are treble shy will probably prefer the mk4, those who want a bit more low end rumble will lean on the Kanas pro. Build wise, both are good but the polished metal shell on the kanas is a step up.
TFZ King Pro
The King pro has a deeper sub-bass and over-emphasized mid-bass compared to the Mk4 but lacks some control in comparison as the mk4 sounds cleaner and more refined. Mids are way better on the mk4 as they are fairly recessed on the King pro and considerably less detailed. Treble on the two is very similar as both maintain good air and sparkle without a tendency to get sharp or strident. Size-wise the king pro is a bit smaller than the Mk4 but makes up for it by being heavier and to my ear the mk4 is more comfortable for long periods as a result of the weight difference.
The b400 comes closer to neutral than the mk4 but does so by sacrificing extension at both ends. Both have good detail although I think the mids are slightly more detailed on the Mk4 when compared side by side. The b400 is considerably smaller so those with small ears may prefer it purely because of fit.
The mk4 has better detail than the IT-01s but less sub-bass and a slightly less energetic upper treble. This can be a double edged sword as at times that low rumble is wanted, but the mk4 has better overall control of its bass than the Ibasso so comes across as cleaner if slightly less potent. The IT-01s is slightly smaller which may be a consideration for some and both are equally well constructed and polished.
The Mk4 and FH5 sport very different signatures, while the FH5 goes deeper, it again loses out on mid-bass details and control when compared to the Mk4. Mids on the Mk4 are hands down better as the FH5 is inconsistent with lower mids being more recessed and upper mids pushed forward comparatively. Treble on the FH5 is recessed at around 5hZ while the dip on the Mk4 is closer to 7kHz which gives the mk4 a bit more open feeling at the top end. Size wise both are fairly close so neither is likely to be a much better fit than the other.
Thoughts / Conclusion:
I’ve listened to and reviewed a few products from Kinboofi before and was honestly the beneficiary of a typo as I had discussed reviewing the Mk3 which is available from a couple sellers on Ali-express. Instead somewhere along the line a 4 got swapped into the conversation and I received them to try and to review. What a great mishap as this is one of the better options available in the $200-250 price range at present. Tuning is very near neutral with the ability to push either the top or bottom end slightly to match your desired tuning using the pair of switches on the back. Build quality is what you would expect from a hand-made and finished in-ear with shell quality being on-par with the other hand-mades I have such as the Eartech Universal and Empire Bravado. Overall, very clean, detailed, and well textured with no major faults to speak of. If I had to nitpick, size is on the large side for a 4BA design, but not so much so as to be something I would shy away from for all but the smallest of ears. A hearty well-done to Kinboofi for a very solid product in a very tight market space. Now about that Mk8…