Exceptionally compact, Great build quality, Case friendly, Low OI and low noise floor, Great EMI resistance, Balanced sound
Small soundstage, Still a very faint hiss noticeable on especially sensitive IEMs
The TC35i is one of the most compact and economical options that nails the fundamentals of a good portable source.
DD Hifi experienced a very quick rise to fame, producing a series of audio accessories that either satisfied niches or innovated upon existing designs. The TC35B was their first source device and I walked away impressed by its balanced audio performance and diminutive form factor. In fact, DD calls this the smallest DAC/AMP design on the market, something that isn’t difficult to believe when handling the device. Hot on its heels comes the TC35i, featuring the same minute form factor, sturdy stainless-steel construction but new internals and Lightning connectivity. As with the B, the I variant offers a nicely balanced experience at the same reasonable asking price.
The TC35i is available for $39.99 USD on DD HiFi’s Aliexpress store here.
I would like to thank DD very much for their quick communication and for providing me with the TC35i for the purpose of review. All words are my own and there is no monetary incentive for a positive review. Despite receiving the adapter free of cost, I will attempt to be as objective as possible in my evaluation.
Coming from the TC35B, buyers will be greeted with a basically identical experience here with exception of the connector. That means that the i variant boasts the same dense, solid and robust stainless-steel construction with handsome brushed finish. As before, gold faceplates denote the year of manufacture alongside the model number while providing some visual intrigue. The only distinct difference is the lightning connector as opposed to USB-C.
The TC35i is also case friendly with a protrusion above the connector and the jack feels to be of the less particular kind similar to later revisions of the TC35B. The downside to a cable-less design here is that it places more stress on the port of the device. However, the short length of the adaptor does mitigate this as much as possible and the Lightning connector has been one of the more reliable standard in my experience. Overall, the TC35i is extremely compact and easy to live with while feeling solid, reliable and built to tolerate the stressors of daily life.
The TC35i was plug and play on my iPhone XS, iPhone 6S and iPod Touch 6G. Given the connector, I wasn’t able to test with windows devices nor are any adaptors that would make this possible available to my knowledge. As with the TC35B, the device only powers on when a plug is inserted. The jack was reliable with no scratchiness or other introduced noise. Similarly, I didn’t find the TC35i to pick up EMI interference which is always a concern with amplifiers connected to smartphones; the metal shell is doing a great job here.
On the flipside, the TC35i powers off when the attached earphones or headphones are disconnected. Unlike the TC35B, however, remote commands do not appear to be supported. I tested using the Shozy Hibiki MKII that worked perfectly fine through the iPod’s integrated jack but would not register at all through the TC35i, this feature also isn’t listed on DD’s website. This is likely due to Apple’s own certification that may have elevated the asking price. No app is available at this time so users are unable to alter settings, gain, etc. I found the TC35i to provide a very usable volume range that said.
Readers will also note that no specifications are listed on DD’s website. After a conversation with the company, we determined that the TC35i is utilising the same internals as the stock iPhone dongle. Actually, this is quite a good thing, the Apple dongle has measures very well and features both a low output impedance (0.9ohms) and noise floor. The main caveat for many is the flimsy build quality with a thin, rubbery cable between two plastic connectors. The TC35i will be a substantially longer-lasting component with no wires and, therefore, fewer points of failure. It is also slightly more compact when taken as a whole. The question here is also whether it upholds the same audio quality as quality always varies between implementation, more on this below.
I think with a product of this kind, it’s most important to firstly keep our expectations in check. I’m not expecting great driving power or a huge soundstage but it’s important to nail the essentials; a linear frequency response, low-output impedance and minimal hiss. In the following sections, we’ll determine how good this adaptor is as a source objectively, then compare with similar alternatives to gauge price/performance.
Frequency Response –
Testing Methodology: RMAA via Startech External Sound Card
The TC35i has a linear frequency response, meaning that there is no intentional colouration added by the source. Similarly, there is no roll-off to be observed for a transparent and balanced sound. Of note, channel imbalance was not noted in listening but may be due to a defective audio cable used during measurement. Due to the quality of my sound card, I am unable to reliably test other measures such as distortion and cross-talk so they will be used as a personal reference only. Qualities here can impact the sound in subjective listening.
Output Impedance & Hiss –
Testing Methodology: SPL volume matched comparison through an inline splitter to THX 789 + Khadas tone board to Campfire Audio Andromeda
Listening with the Campfire Audio Andromeda revealed a very low output impedance likely around 1-ohm. There was no noticeable change in sound signature relative to the 1-ohm THX 789. In addition, the noise floor was very low, with only a faint hiss on the Andromeda perceptible at the very lowest volume setting, it is also a lower-frequency hiss so not as intrusive as some. Those particularly sensitive to hiss with very sensitive IEMs such as the Andro can investigate other dongle options that have a black background. That said, the noise here was similar to the iPod’s integrated audio solution which is already quite quiet, and also quieter than the TC35B. This makes it a good choice for all but the most sensitive IEMs that will experience faint hiss but no other colouration.
Testing Methodology: SPL volume matched comparison through an inline splitter to JDS Labs Atom + Khadas tone board to Custom Art Fibae 7 (flat impedance)
Many listeners consider the Apple dongle to offer strong sonic performance and this is the case in my experience too. Sure, it’s no desktop rig and dedicated DAPs will handily beat it out, but in terms of the fundamentals, there isn’t too much to complain about. The TC35i continues this experience, it is a linear sounding source with a clean and well-balanced sound.
The low-end is balanced and even-handed in its expression. There isn’t any notable emphasis or colouration to speak of. Compared to the desktop setup, there isn’t the same sense of sub-bass extension that said. In turn, bass notes are not as bold or weighted. Rumble and slam are slightly diminished, and the stage assumes a shallower, less grand presentation. That said, bass is not especially lacking when not in direction comparison. This also provides is a slight increase in mid-bass separation as bass notes become a touch smaller. Again, do not take this as the TC35i being a lean or bright source, this is a fairly typical experience when switching from a desktop to portable source. I am noticing greater definition and control on the THX amp too, the TC35i smearing over fine details to a noticeable degree. The desktop source simply sounds a lot more dynamic and organised with higher resolution. The TC35i is doing an admirable job here with good extension and linearity that is certainly not a given on sources this compact.
In accordance with its slightly less prominent bass, the midrange assumes a slightly thinner character, albeit not a dry or strained one. Again, the source appears linear and devoid of tonal colouration. Vocals simply aren’t quite as powerful and full-bodied, the stage again lacks depth when compared to the more voluminous and extended desktop source. Vocal size is a touch reduced, in turn, however positioning is accurate on a whole, so localisation is a good performer and the TC35i takes good advantage of its limited sense of space. Timbre is, to some extent, what some source afficionados would call “digital” sounding, albeit not a glaring fault unless you specifically want high coherence. The TC35i upholds quite a natural voicing alongside good definition and positioning. It is not outstanding, nor would I expect it to be. It is simply nicely balanced and tonally transparent which makes it a good performer in my books.
Highs are just a touch forward to my ears, albeit well-bodied and detailed. The foreground appears to have a uniform boost, bringing treble instrumentation just a touch forward relative to the THX, albeit this may also simply be in reference to the TC35i’s smaller bass. Still, as there remains good linearity, instruments are portrayed with accurate body and impressive amounts of texture. Fine detail retrieval is also quite good, albeit the desktop source appears to have an appreciably higher resolution. It is more discerning of background details especially, aided by its larger soundstage that provides better separation between elements. Though the TC35i is balanced, its smaller space can mean it becomes congested on complex tracks that the THX amp effortlessly resolves. Otherwise, you do get ample sparkle, good detail retrieval and a very pleasing representation of foreground instrumentation.
The soundstage is immediately a lot smaller than the THX 789, and this is especially apparent when listening from a high-end IEM like the Fibae 7. Width stretches just to the periphery of the head where the THX is able to render well beyond. However, I actually found that it was depth that was most limiting. Vocals simply don’t have the same level of dimensions and layers are not especially well separated or defined. Imaging is accurate as is localisation, directional cues are sharp. Separation is harmed by the smaller dimensions of the soundstage, albeit not a poor performer in isolation due to the clean tone and accurate note size throughout.
Driving Power & Suggested Pair-ups –
DD don’t state the TC35i’s specifications or output power on their website and weren’t able to clarify these details to me either. Still, much like the TC35b, I found it to reliably power IEMs and portable headphones. Full-size headphones remain a bit too challenging but there is ample power to achieve high listening volumes and good driver control.
Moondrop Starfield (122dB, 32 ohms): A sensitive and easily driven earphone with good driver quality, the Starfield reached comfortable listening volumes for me at around 20% volume. The TC35i provided a good experience here, bass was well-extended and controlled with a nicely defined mid-bass. Sub-bass lacked a little power, but remained well pressurised and impactful. Mids were slightly thinner but still naturally voiced and coherent. Vocal definition is enhanced in exchange for reduced coherence overall. Treble is a touch more prominent but well textured. The soundstage is more intimate but the sound isn’t congested due to the slightly thinner midrange and sub-bass that increases separation. Overall, not the most expansive or dynamic, but a well-balanced and transparent sound.
Final Audio E5000 (93dB, 14ohm): The E5000 requires a good amount of volume and driving power to reach ample listening volumes and tighten up its bass. I was comfortable at around 40% volume. Being a single DD, the signature was identical. The THX was noticeably more controlled, in fact, the TC35i provided a bigger, bassier experience here. Bass also has slightly quicker attack on the TC35i but was still less defined and detailed overall with slight mid-bass smearing. The midrange reflected my experiences with the other pairings, being slightly thinner but also with an uptick of vocal clarity. The top-end was also a touch forward and noticeably more textured on the THX. Still, there remained good detail retrieval and contrast between foreground and background. The soundstage was more intimate, but still quite spacious due to the E5000’s inherent qualities. Separation was good throughout too.
Audeze LCD-1 (99dB, 16 ohm): The LCD-1 is quite easy to drive but does still scale well with a good source due to its resolving power. I found myself content with 35% volume, leaving plenty of headroom for quieter songs or those preferring high listening volumes. The bass was similar in quantity to the THX, albeit with a little less sub-bass presence and power. The mid-bass, however, was noticeably looser with less definition, glossing over fine details. The midrange was coherent and well-bodied. I noticed a clean tone and presentation here, no complaints. The THX amp offered more depth. Treble was also similar in quantity to the desktop source. Foreground detail retrieval was very good, even fine detail retrieval, there was a little more texture and resolution on the desktop amp. Once again, I found the TC35i providing a noticeably smaller soundstage, not too noticeable on the LCD-1 that doesn’t have the grandest stage to begin with. However, depth was noticeably reduced as was separation in the treble especially. Given that the signature is balanced, the TC35i does well in a pinch though, of course, a dedicated desktop amp setup does a much better job when it comes to critical listening and immersion.
DD TC35B ($39): The TC35B provides higher power output with 25% volume being roughly equivalent to 35% on the I, and maximum volume being about 2 notches higher too. The sound is fairly similar at a glance. The TC35B is a touch more coherent to my ears while the TC35i is a bit more balanced and tonally transparent. The TC35i provides a slightly quicker bass, but also a touch less depth and power. The TC35B is a smidge warmer and has a more coherent midrange while the TC35i is slightly clearer and more open. Treble is similar between the two in terms of presentation, the TC35B offers a slightly higher resolution and detail retrieval but most listeners would be challenged to differentiate the two without a splitter. The soundstage is slightly larger on the TC35B.
Fiio BTR3 ($55): The BTR3 provides a deeper, more substantial and slightly warmer bass. It has thicker notes and greater dynamics while the TC35i is cleaner and more balanced but also lacking the same impact. The midrange is fuller on the BTR3 but similar in positioning. It has a bit more depth while the TC35i has slightly higher definition and a more neutral tone. The top-end is more refined on the TC35i, having sharper and more aggressive attack on the BTR3 but also a bit of grain and less fine detail retrieval. The TC35i is more balanced and textured here. The BTR3 has a slightly larger and noticeably deeper soundstage while the TC35i has slightly better imaging.
DD HiFi are becoming a very reliable name, the company producing consistently good products since their inception. The TC35i continues this trend, offering a slightly stronger experience than the Type-C variant due to its slightly lower output impedance and noise floor. However, in so doing, it does have a lower output power and slightly smaller soundstage. The value proposition here is also debatable, depending heavily on buyer priorities. The stock Apple dongle is essentially sonically identical at a third of the price. The price premium brings a much more robust build and an even more compact design but minimal benefit to sound. So, the TC35i makes sense if you enjoy the sound of the stock dongle, which itself represents a sound performer, but find yourself having to frequently replace them. Conversely, if your i device didn’t include an adaptor at all, the TC35i is one of the most economical options that nails the fundamentals of a good portable source.
The TC35i is available from on Aliexpress (International) for $39 USD at the time of writing. I am not affiliated with DD or Aliexpress and receive no earnings from purchases through this link.