DDHIFI TC35 dongles and DJ- adaptors provide unbeatable build quality, ergonomics, and portability
Introduction
In the world of digital audio, accessories, particularly those that are implemented somewhere along the signal chain, can be a tricky topic. On the one hand, if they work well and get the job done, then they've successfully served their purpose. But on the other hand, there are audiophiles who swear on the effect of accessories on the audio quality and even sound signatures of their transducers. Cables and dongles are easy examples of such dichotomy. In this post, as we take a look at the lineup of DD Hifi dongles and adaptors, we'll do our best to examine both sides of the spectrum and address both the functional and the nitty gritty audio aspects of these products.
DDHifi
DD Hifi is brand that, up until recently, has focused predominantly on producing audiophile accessories such as cases, dongles, adaptors, and cables. Albeit its narrow market scope and target audience, the few products that DD Hifi produces are known for their remarkable build quality. Take for instance their TC35-dongle or the DJ-adaptor lineups, which are both produced almost entirely of single blocks of stainless steel and feel nearly indestructible. The precision of design for both types of accessories are so well defined that often times their mechanical connections feel more secure than even those of OEM accessories. Furthermore, the biggest appeal for these accessories are their ultra-compact form factor, which is attributed to the lack of cables in the design and well thought out product designs. DD Hifi has undoubtedly mastered their craft.
DJ-Series Adaptors
We'll get straight to the point. These are adaptors - things that let you change your cable plug type, be it 2.5mm, 3.5mm, or 4.4mm, to that of another. They aren't that complicated, and if they work, then they work.But the genius of the DJ- series of adaptors by DD Hifi is in its design. First, they don't utilize cables connecting the female to the male jacks; it's one small piece of clear plastic and metal. This eliminates two major issues with traditional adaptors that utilize intermediary cables - 1. potential for the adaptor cable to get frayed and damaged over time with use (which is one of the biggest reasons why people get new adaptors). - 2. If you're an audiophile that values cable material and their effects on audio quality, you no longer have to worry about matching the cable type to that of the adaptor. There are other adaptors in the market that feature a similar cable-less design, but the major issue with them is their implementation. Often times, they are long pieces of metal that plug in parallel to your device' jack, which in the end makes your entire setup look like a long antenna pole - a particularly uncomfortable situation with portable DAPs. All of the DD Hifi's adaptors are designed to connect perpendicularly to the device input jack, which makes for a much more ergonomic usability. And finally, many cheap adaptors suffer from faulty termination connections, which cause one channel to not transmit or the connection to go in and out. In all of the DD Hifi adaptors we have tested, we found the termination points to be entirely secure, and have yet to experience any issues in the audio transmission.
TC35- Dongles
Now this is the tricky part. With adaptors, if they relay a clear signal without adding any noise or potential mechanical fault, then they're good. But with dongles, we begin to wade into the question of audio decoding and quality. Let's start off with the easy part - build quality. The TC35 series (which comes in USB-C or Lightning, both available with 3.5mm or 2.5mm options) are simply the best dongle designs available. They are definitely the smallest dongles out there, and they feel quite indestructible, being constructed out of a single piece of stainless steel. They have long enough connection jacks that accommodate phone cases, and best of all, they're cable-free. I'm currently on my third Apple Lightning dongle and always because the cable on the dongle wears out from being bent and shoved in my pockets. This is an issue that you'll never face with the TC35- series dongles. Now on to the hard part. In all honesty, I went in not expecting to measure or hear any differences in audio transmission between standard device headphone jacks/OEM dongles and the DD Hifi dongles. Comparison of the 2020 MacBook Pro 16" model headphone jack with the TC35B (USB-C to 3.5mm) surprised me, as the TC35B showed a slightly lower noise floor compared to that of the Macbook's headphone jack. 
Furthermore, measuring the raw Total Harmonic Distortion (THD) from both ports show that the TC35B also has a slightly lower THD than the Macbook's headphone jack. (Macbook Headphone Jack) 
(DDHIFI TC35B) 
Additionally, the audio format on the MacBook Pro's headphone output is limited to 32bit 96kHz, while the TC35B can be configured up to 32bit 384kHz. 
When listening, this made a huge and immediate difference in the perceived sharpness, detail, and resolution across all of my IEM's. The TC35B sounded immensely more crisp across the spectrum, but particularly, bass felt much snappier and upper harmonics had more shimmer and airiness. Now having stated this, it is unclear whether the 2020 MacBook Pro 16"'s headphone port is simply subpar, or if the TC35B is above standard. It might be possible that these measurements and perceived effects are less pronounced or even non-existent for other USB-C devices. But what's clear is that at least with the MacBook Pro, the audio quality alone is reason enough to grab the TC35B.
DDHIFI TC35i vs Apple Dongle
In comparing the TC35i (Lightning to 3.5mm) to the Apple Dongle on the iPhone 11, both measurements and perceived audio differences were minor. Both dongles had comparable Noise Floors when measured at the same volume setting on the iPhone, although the TC35i did produce a greater SPL than the Apple dongle. 
THD levels were also comparable between both dongles. (Apple Lightning to 3.5mm Dongle) 
(DDHIFI TC35i) 
In listening to both dongles, it is possible that the TC35i did sound crisper than the Apple Dongle, but also a with a slightly smaller soundstage. IF I had to describe the sounds of both dongles, the TC35i could be a little sharper while the Apple Dongle feels smoother in nature. However, across all of my IEM's, these differences were so minor, that I cannot advocate the purchase of the TC35i solely for its audio improvements over the OEM Apple Dongle.
Conclusion
If your intention on purchasing a new dongle is for audio improvements, the TC35 series may or may not fulfill that need, depending on your device and its standard headphone port. Nonetheless, the TC35 dongles and DJ- adaptors provide unbeatable build quality, ergonomics, and portability. You could toss the TC35's into your pockets or bag for the rest of your life and you would probably never have to replace them. 
