AUX extension cable mod for Sony MH755

After having tried many different AUX extension cables, I really like this short 0.5m 3.5mm male to female AUX extension cable from DTECH. The TPE material is nice and soft and blends well with the MH755 cable unlike the fabric ones that sorely stand out.

Please note that this is a 3.5mm 3 pole (TRS) cable and doesn’t work with 3.5mm 4 pole microphone (TRRS) connectors.

Azla SednaEarfit XELASTEC – Initial Impressions

The Azla SednaEarfit XELASTEC are some of the grippiest wide-bore tips I’ve come across and as far as I know the only ones made of TPE (thermal plastic elastomer), which means they softens with body heat and change shape to fit your ears (unlike urethane foam tips that changes the shape of the ear canal).

I find, I need to choose a size smaller (MS) for these than the JVC Spiral Dots (M). I think this is because the Sprial Dots are spherical (hence wider) while the Azla’s are cylindrical.

Tyll would have loved the ER2XR

While reviewing the Etymotic ER4SR and ER4XR here is what Tyll had to say about bass response:

For me, the bass level on the ER4SR simply isn’t enough. Frankly, even the ER4XR doesn’t have enough bass for me, but it’s much better. I believe quite strongly that bass response on headphone should have about a 5dB bass boost below about 150Hz.

Tyll Hertsens in 25 Years of Making a Good Thing Better: The Etymotic ER4sr and ER4XR on Page 2

Tyll would have loved the ER2XR 🙂:

When the ER4XR was launched, Tyll applauded Etymotic for making the brave move of catering to user preferences and deviating from that they believed to be technically “accurate”. I think Etymotic went further with the ER2XR (and it’s almost like they took his feedback into account) and for that I am grateful as the ER2XR has just the right bass response for my preferences 🤗.

For me, having over 20 years of close experience interacting with Etymotic and the ER4 product evolution, I find it an interesting example of corporate learning at work. On the one hand, Etymotic has very strong reasons to believe they have a grip on what “accurate” means, on the other, they have 20 years of experience with customer feedback about the desire for more bass. Adding bass willy-nilly is simply not something this audiometry company would do; but having strong feedback that customers want more bass can’t be denied either. Making the corporate decision to deviate from technically accurate to cater to user preference is actually a pretty brave move from their point of view. I applaud this development!

Tyll Hertsens in 25 Years of Making a Good Thing Better: The Etymotic ER4sr and ER4XR on Page 2

Seekers vs. Tinkerers

You can judge IEMs/headphones on whether they sound good to you out of the box or also on their potential.

People from the former camp (seekers) might go down the path of finding the ones that perfectly match their preferences. IMO, the probability of this is so low that it seems futile to chase the perfect match. At best they might find something that is close to some of their preferences, but not others.

People from the latter camp (tinkeres) recognize they might not find the perfect match and are willing to put in the work to take advantage of potential. They do this either via EQ or modding. A prerequisite for this is potential. You might be able to fix tonality to some extent but you can’t fix things like technicalities, coherence, etc. if there isn’t a potential for it. Even tonality might not be fixable in some cases.

Some good example of tinkeres are james444 and the folks over at and a great example of an IEM being recognized for it’s potential is the JVC HA-FD01 which was modded by james444 and eventually resulted in the now legendary Drop+JVC HA-FDX1.

Of course there are many other dimensions along which to categories ourselves in the hobby but I think this is an interesting dichotomy to highlight.

So which are you, a seeker or a tinkerer? Are there better terms for these?

QKZ VK4 vs Sony MH755 (SBH56) Measurements (Frequency Response Graphs)

So I took out the QKZ VK4 today to measure (using my DIY-tube rig) and I was pleasantly surprised to see why I remember liking them.

Note: The graphs don’t accurately represent what you might hear and are only representational. Improving them is an ongoing process.

Measurements taken using pre v0.1 of my DIY IEM measurement rig

TRV VX – Review


  • Driver unit: 1DD 6BA Hybrid with a proprietary active crossover circuit
    • 1 x customized 10mm dual-neodymium magnet dynamic driver
    • 3 x customized 30095 BAs for high-frequency
    • 3 x customized 50060 BAs for upper-mid-range
  • Impedance: 22Ω
  • Sensitivity: 107dB/mW
  • Frequency Response: 7Hz – 40000Hz
  • Connector type: 2 pin type-C 0.75mm with gold plated pins
  • Cable:
    • Material and Build:
      • OFC (Oxygen-Free Copper)
      • Plastic sheath
      • Braided 4-wire to braided 2 wire above y-spliter
      • Memory-wrap Earhooks
    • Termination: 3.5mm gold-plated straight plug
    • Length: 1.25m
  • Earpiece: 5-axis CNC Machined Aerospace-Grade Magnesium Alloy Housing
  • Weight: 28gms
  • Available Colors: Dark Green, Knight Black, Vibrant Blue (haven’t seen this color anywhere though)
  • In The Box: Earpiece, cable and 3 pairs of eartips (S/M/L)

Non-audio Aspects

  • Packaging and Accessories: The packaging and accessories are underwhelming given other IEMs in the same price range (like the KBEAR Diamond, for example) but I’m guessing that’s the price you pay for having more drivers. The cable is also very basic and apart from having a different plug and connectors, it feels exactly like the one that comes with Blon BL-03, with the stiff memory hooks that make it prone to tangling. The stock eartips are not bad and work well for me.
  • Earpiece Build and Design: Really good build quality and quite a looker (subjective).
  • Driver Flex: I rarely experience driver flex on the VX.
  • Cable Noise: The VX is designed to be worn over the ears so you don’t get any cable noise.
  • Comfort and Fit: The VX fits very well on my ears, is light and very comfortable (Note: This is very relative to your specific ear shape)
  • Isolation: Fits very snugly in my ears so isolation is good for me. With music on, I can barely hear what’s going on around me.
  • Efficiency: Easy to drive with most smartphones and doesn’t require an amp.

Review Setup

  • Chain: (Phone|Laptop) > Spotify Premium (Downloaded, Quality: Very High) > Meizu Hifi Pro DAC > IEM
  • TRV VX: Stock cable and eartips
  • Reference: Etymotic ER2XR with stock triple flange regular tips.

Tonality & Technicalities

Sound Signature

To me, it sounds like the bass is boosted but not as much as the upper-mids and treble, and the lower-mids are slightly recessed. It doesn’t sound as coherent as single-DD IEMs and the bass can sound disjoint from the rest of the range.


Bass is boosted but not too much and well extended. It’s fast and pretty linear with no sign of boominess or bass-bleed. While I prefer the sub-bass focus, it might not be a very natural presentation. Drums and bass guitars sound a little muted and the upper harmonic focus doesn’t lend itself to a very organic sound.


The lower-mids are slightly recessed while the upper-mids are substantially boosted and the midrange has a very forward and detailed presentation. The cut in the lower-mids makes instruments and vocals that have their fundamental in that area sound thin. The substantial boost in the upper-mids results in instruments like electric guitars sounding a little shrill/aggressive. On some tracks with female vocals, I really like/enjoy the wet presentation as it adds a visceral dimension to the voice.


Treble is boosted, aggressive, detailed and decently extended. The emphasis in this area coupled with the faster BA decay, can make instruments sound unnatural but also results in more clarity and detail. The treble boost makes certain instruments standout in the mix in an unnatural way, which can make some tracks interesting and not so much for others. It can be borderline siblant but I don’t think it crosses over to being siblant. Cymbal strikes are splashy and not as harmonically rich and resolving.

Soundstage, Seperation and Imaging

Soundstage is out-of-the-head both in width and depth with decent separation and imaging. However, the sense of space is not realistic. A performance in a theater doesn’t sound like it’s in a theater. I suspect this is because of the spikes in the treble region.


The TRN VX can be a fun/aggressive/analytical sounding IEM that trebleheads might enjoy. The upper-mids and treble boost will most likely be harsh and fatiguing, especially for people that are sensitive to that area. Those who enjoy the coherency of a single-DD may find the bass disjoint from the rest of the range.

Where to Buy

You can buy the TRN VX from the TRN Official Store.



  • TRN VX Measurement
  • Cross-referenced list of tracks and notes
  • “See Also” section with:

Biases I’m Aware Of

  • The TRN VX unit was sent to me by TRN for review.
  • I know KopiOkaya, the tuner of TRN VX.
  • I moslty own, listen to and prefer single-DD IEMs, and “believe” BAs don’t sound “natural/organic”.

Known Issues

  • Volume matching was done by ear.