Tempotec Sonata HD PRO

Introduction
Do you guys also experience annoying noises in your audio when using the audio input on your phone (for those who still have phones with a headphone jack) or on your PC? Well, that's exactly what was happening to me two years ago, particularly with in-ear headphones that tend to have low impedance and high sensitivity, which makes them extremely sensitive to any signal transmitted by the device they are connected to.
This little guy saved my ears: this is a review about the TempoTec Sonata HD Pro (yes, I am a little bit late to the party haha), a dongle dac/amp that goes for $39 (but can be found in AliExpress for $30)



Unboxing, build and accessories
This dac/amp dongle comes in a cute metal box, which contains the device itself, a micro USB to USB-C adapter cable, a USB-C to USB-A adapter, and a sticker. The dongle has an awesome built for $35 USD, it has a good black metal construction with two buttons that allow for volume control, and it doesn't look cheap at all. Furthermore, from my personal experience, I can attest that it is very durable. I have taken it on trips several times and it has even fallen to the ground during a rainy day, yet it still works just like the day I bought it.




Specifications
The TempoTec Sonata HD Pro is a dongle that performs a double function: it serves as a DAC (Digital to Analog Converter) and also as an amplifier, providing a power of 2Vrms (110mW at 32Ohm on high gain mode), making it an ideal companion to use with a wide variety of headphones, from in-ears to over-ears that do not have very low sensitivity (+95 dB (1kHz/1Vrms)). It also has DSD 256 decoding and offers a resolution of up to 32bits/384 kHz.

Performance (music and gaming)
This little guy can give you more volume than you can ask for in almost any portable situation that I can imagine. On my phone, I can only listen at 25% of the volume level provided by the phone at maximum. How is this possible? Let me explain.

As mentioned, the dongle has buttons to control the "steps" that can be taken in volume. However, what I did not mention is that those buttons only control the volume that belongs to the dongle, leaving apart the volume of the device it is connected to. Ideally, the dongle volume should be at max and the volume of the device connected to should be the one to be regulated. On my phone, I can only turn up the volume four steps at most before it gets too loud for me (which represents 25% of the 15 volume steps of this device), while in Windows, I can only raise the overall volume up to 10-12, which is insane!

As for the headphones I used with the dongle, they include Sennheiser HD 558, Hifiman HE400SE, KZ DQ6, Moondrop Aria, and HZ Sound Heart Mirror. Of these, only the HE400SE seemed to need more powerful amplification (even with the high gain trick applied) given their magnetic-planar driver technology, but for the levels at which I listen to music, they worked properly.

The best aspect of this little guy is the practically non-existent floor noise it has. This was a blessing for me because when I started taking this hobby more seriously, I couldn't use any type of headphones with my phone due to the high and annoying floor noise it had. That noise was reduced to something inaudible thanks to the Sonata, and the best thing is that it is also compatible with Windows, so I could use it on multiple devices.

One pleasant surprise with this dongle was how well it worked on Windows. For that reason, I started using it for gaming and really felt a difference in competitive games, shooter games in particular. With such a low noise floor, enemy footsteps or combat situations in Battle Royale type games became much more noticeable (some may consider this a competitive advantage).

In technical terms, the sound profile tends towards analytical, without colouring the sound at all. It presents a wide soundstage (but not as wide as a desktop dac/amp) and good amount of detail in the treble region for such a small device. As a dongle with a colder profile, the voices and instruments don’t have that warmth that many people prefer but is suited for those who like to analyse the music and all of its sounds in detail.

One issue I encountered was that without updating the firmware to the latest version (which can be found on this page: http://www.tempotec.com.cn/chs/4-Company/driver.htm , thanks to user ALC220 who made this link available in the comments on Audio Science Review), the dongle suffered from many cutouts when connected to my phone. After updating the firmware, the presence of cutouts/popping noises decreased significantly but is still audible when fast forwarding or rewinding a video or music track.

Finally, if any other defect has to be mentioned, it could be that the device has an "old" input (micro USB) and that it can heat up when in use due to using the phone battery or PC power to work, but as far as I'm concerned, it doesn't get to the point of bothering me at all.

High gain trick
This "trick" is already well known in the audio enthusiast community and consists of the following: this dongle has two modes, one that recognises low impedance headphones and another that recognises high impedance headphones. The latter offers more power when amplifying headphones, so wouldn't it be convenient to be able to always use it? In order to achieve that, we just have to connect a 3.5mm cable without the headphones connected to the other end, which will make the dongle go into "high gain" mode, then connect our headphones to that same cable and voila!

Conclusion
In summary, this little device gets my recommendation. It allows for a high level of portability with tons of power and a noise-free DAC that simplifies the life of those with audio ports problems like mine.

Link to my review and measurement index thread where one can also find a full review overview, more information about myself as well as my general-ish audio and review manifesto: https://www.head-fi.org/threads/956208/


TempoTec Sonata HD Pro


Source:

Purchased at a discount for the purpose of a product review.


Miscellaneous:

Unboxing experience nicer than expected – decent packaging with accessories such as a micro USB to USB-C cable, USB A to USB-C adapter (made of metal just like the cable’s plugs) and a Hi-Res sticker.
A cheap feeling carrying case that is made of metal is included as well – I would have preferred a zipped pouch or hard case, but it’s still better than nothing at all, and nicely padded on the inside.

Nice build quality and finish.
I like the design.
Nice translucent orange volume control buttons.
I don’t like the big DSD logo etching on the back of the device.
Reasonable size.
What I really like is that the female micro USB socket feels solid and that one can use any suitable cable with the DAC.
Short connection cable is supple and looks nice.
Unfortunately there is no LED/operation indicator.

What’s definitely nice is that it automatically detects whether a 3.5 mm plug is inserted or not and accordingly enables/disables the output (doesn’t show up in the Windows sound menu anymore if the headphone jack is plugged out).




Sound:

My ZOTAC ZBOX CI547 nano running Windows 10 Pro 64 Bit is the only source that I’m using.

I’m only using my Sonata HD Pro in 16 Bit 44.1 kHz mode, just like any other DAC that supports the Red Book standard.

Volume Control:

Independent hardware volume control on the HD Pro (12 steps without any muting feature) in addition to the source device’s digital control.
Coarse steps; I would have wished for more than 12, but ultimately the independent control is a definite plus as it allows for finding a desirably quiet listening level even with extremely sensitive in-ears as well as quick volume adjustments while listening to music or watching a film without having to interfere with the Windows software slider.

Tactile activation point neither too stiff nor soft – ultimately somewhat more on the stiffer side.

The last volume setting seems to be saved.

Hiss Performance:

Practically hiss-fee – even less audible hiss than my Apple USB-C to Headphone Jack Adapter (A2155) that is already among the very best devices on the market when it comes to hiss performance with extremely sensitive in-ears (such as my Campfire Audio Andromeda and Ostry KC06A) regardless of price point. Hiss only becomes more audible with extremely sensitive IEMs when used at higher hardware volume control settings.

Even quieter than my RME ADI-2 DAC from its PHONES output and just a hair “hissier” than its IEM output that’s basically hiss-free (just the tiniest, slightest imaginable bit of hiss audible with my Andromeda on some days with very high concentration) – that’s definitely state of the art hiss performance and among the best of the best devices in this regard.

Frequency Response (no Load):



No surprise here – as flat as it is supposed to be, with a slow roll-off filter applied.

Output Impedance (Ultimate Ears Triple.Fi 10 as Load):



Based on the frequency response deviation, the output impedance is calculated to be below only 0.2 Ohms, which is very low and therefore perfectly suitable for all low impedance multi-BA in-ears with a high impedance swing.

Subjective Listening Impressions:

Neutral, clean and audibly transparent with no abnormalities that could be heard. No real surprise since independent objective measurements indicate excellent performance anyway.

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Compared to my Apple USB-C to Headphone Jack Adapter (A2155):

With the Sonata’s software volume being set to 100% and its hardware volume to 1/12 and, and the Apple’s volume set to 1%, the Sonata’s base volume is lower, which is a definite benefit for me, and since it can be further lowered using the Windows software volume, listening very quietly just barely above the audible threshold is easily possible even with extremely sensitive in-ears.

Sonata ever so slightly “softer”/”smoother” cymbal/high note edge rendering in direct head-to-head comparison with extremely sensitive, low impedance in-ears – Apple “harder”/”sharper” in comparison, which is about the only “big” audible difference in terms of small, subtle differences that one may or may not perceive (pretty much only) in a direct head-to-head comparison (definitely a matter of individual preference, and I slightly prefer the Apple’s “harder” presentation in a critical listening, direct a-/b-comparison scenario whereas I don’t care much at all for concentrated but more recreational music listening), with the only other nuance of differences that I can perceive in this forced direct comparison being the spatial reproduction that appears slightly smaller but with a more “focused” centre image on the Sonata aHD Pro nd a “wider” presentation on the Apple that however results in a slightly “less focused” centre image image presentation when compared to the HD Pro (something that I personally probably prefer on my TempoTec a little over my Apple, but then again only really in a direct “critical” comparison whereas the small difference in spatial reproduction becomes much less obvious with a bit more time between switching between these devices).

Take what you want out of this more “critical listening” focused direct comparison (conducted with very sensitive, low impedance in-ears – as it is true in most cases, there should be no audible differences with inefficient, lower sensitivity full-sized headphones since those minor differences described just above that may be audible in a direct comparison when extremely sensitive low impedance IEMs are used as critical loads are already gone entirely when I use both devices with less sensitive, higher impedance in-ears) – what’s very clear though is that both devices are perfectly clean and audibly transparent, neutral sounding.

Realistically speaking, the Apple USB-C to Headphone Jack Adapter (A2155) already offers nearly top-tier audio performance despite its super low price (after all it is audibly transparent thanks to objectively surpassing CD Red Book standards and) and is only despised by some people because of their anti-Apple and anti cheap audio products bias; so except for being even closer to being entirely hiss-free with extremely sensitive in-ears than the Apple dongle already is when an “empty” audio file is played, it is mainly some additional useful features (additional and independent analogue 12-step volume control and micro USB input; although at the cost of some of the Apple’s features missing (in-line remote control commands and in-line microphone support)) and build quality/appearance as well as accessories that make the Sonata HD Pro a device that is worthy of costing more than the A2155, with both performing excellently when it comes to audio reproduction with critical low impedance, high sensitivity loads (the TempoTec even a little more so despite being priced comparatively very low as well).




Conclusion:

State of the art hiss performance with extremely sensitive in-ears, very low output impedance, and otherwise very good objective acoustic measurements as well. Ability to listen very quietly just above the audible threshold thanks to the incorporation of additional independent analogue volume control (unfortunately only 12 coarse steps, though).
Last but not least, the accessible pricing is very fair as well, and even without keeping the price in mind, the Sonata HD Pro is one of the very few small, portable USB DACs that are able to match or surpass the Apple A2155 USB-C to Headphone Jack Adapter’s objective audio performance.


Photos:

About myself

I'm 38, so my hearing is possibly not the same as in my 20s. I like various music genres, mainly prog rock/metal, blues and some classical music. I'm not into rap/hiphop/EDM so I don't have a strong preference regarding excessive bass quantity.

Some background

I've purchased this item myself, it was new. I have no affiliation with the manufacturer nor was this a sponsored review of part of a loan tour.

Unboxing

Although this is a pretty cheap product, the packaging was stylish.

Usability

I had no issues with an Android phone and two Windows 10 machines at all. Works without installing anything and keeps working if you install the drivers.

Unfortunately the volume control is not the best as the "distance" between the steps is too big.

An even bigger problem build quality. The USB port on it was so sensitive to the slightest movement of the cable that it got disconnected (not physically) even if I just touched it. It was impossible to use the unit on the go. I contacted the seller and got a free replacement, I did not even have to send the first unit back. Unfortunately I had the same problem with the new unit too, although not as severely. I did not bother asking for a third one.



Sound

Sound is good, especially for a dongle. Well extended at both ends of the frequency range, clear and transparent.



Pairing

It can drive a HiFiMAN HE400i, a Denon 7200 or a Focal Elegia with enough power and authority. However, it definitely cannot drive a MrSpeakers Ether C.



Conclusion

If you are lucky and get a unit that works properly and have an easy to drive headphone or IEM, then this will be a great companion.