Review - Hidizs S8 Pro Robin

Review - 7Hz 71

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TLDR version on YouTube: TDLR - 7Hz 71

The 7Hz 71 is a dongle DAC that seems to have gone fairly unnoticed, at least I hadn’t heard anything about it until I ended up purchasing it out of pure coincidence. I was actually purchasing something else and to meet the free shipping minimum order, I saw it on sale for around 20€ (if I remember correctly) and added it to the cart.

It has sat unopened for quite some time as I sort of forgot about it. I kept seeing it when I was grabbing something else and it wasn’t until this week, when I was grabbing a couple of dongles for a test, that I decided to finally open it and give it a test.

As this was purchased, I am not going to link to any specific store but it seems to be available on all the usual stores, priced around 30€. Its also available on Amazon in some countries and on Aliexpress (although I did see it was more expensive on AE).

Anyways, here are my impressions of this rather budget friendly dongle DAC from the brand who are better known for their IEMs.


The packaging is a simple cardboard sleeve that shows the dongle on the front and a picture of the internal board on the back. There are no specs shown on the packaging, just the brand and model. There is a small logo in the top corner that says “1st - 2022”, but I am not sure what it was actually first in/at.

Removing the sleeve reveals the dongle covered by a transparent plastic sheet and that is about it. There is actually a card inside the box that does show some specs, which are as follows:

DAC: AK4377

THD+N: -108dB/0.0004% (32 Ohms)

1Vrms (32 Ohms)

70mW @32 Ohms



PCM 32bit/384kHz


There's really not much more to say, copying the specs was more of a content filler than anything else 😉

Build and aesthetics…

The dongle isn’t tiny but it is still rather compact, smaller than many other dongles that I have tried out in the past. Completely made of metal, it is not heavy although it does have a little bit of weight to it, giving that sensation of being well built.

Although it is quite simple in it’s build, 7Hz have given it a touch of aesthetics on the face, with a raised center section that features a single, blue, LED (which I have to say is rather bright). The 7Hz logo is shown in white in the center of the raised section, with a sort of robotic shape to the surrounding area.

The cable is fixed, with a 4cm flat section of cable before terminating in a USB-C connector that also shows the 7Hz logo. I am not sure how long the cable will stand up to abuse in a pocket but with it being flat, it allows for it to be bent and attach the dongle to the back of your phone etc.

I honestly have no complaints with the build or aesthetics with this dongle for the price. No, it is not something that stands out as being beautiful but it does have something going on to break up the simple black box.


There really isn’t much I can say here. You plug it into your device and away you go. I have tried it on various systems, Android and Windows, without any issues of it being recognized.

There is no volume control on the dongle, so you will need to be careful when plugging it in to a Windows device, as Windows has the habit of setting these things to full volume (not this dongle but many dongles).

I have to say that the power draw of this device is pretty impressive, being similar to the Apple Dongle in this regard, with the battery of phones not seeming to drop any quicker than if we were using the normal headphone output of the device (for those devices that still have a headphone output).

The dongle does get a little warm after a while but by no means does it get hot. I think if they lost the LED, it would not get warm at all and the battery consumption would be even less.

Just as a note for those of you that care, the 71 does not decode MQA.


I have to say that I was expecting less from the 71 when I first plugged it in. I obviously had no idea what it would be like as I had never seen anyone speak about it but I was dubious about a 30€ unbalanced dongle that hadn’t found any fame amongst forums (at least that I have seen).

As I mentioned a moment ago, this dongle uses the AKM AK4377 chip, which has been around for quite some time (info dates back to at least 2018) and has been used in quite a few dongle DAC devices and some compact DAPs (such as the Fiio M5). Some of these devices have received a lot of praise, such as the Lotoo PAW S2, which was released in late 2021 and is still a very popular device today.

I mention this because it is not always about having the latest chip for something to be good, in fact, it's very rarely about the chip, it’s more about the implementation. This is something that I have found with many devices that use what some would consider “old technology” but prove that, when done right, they are capable of achieving a great outcome. I feel that the 7Hz 71 has proved this once again but at a much lower price point.

Ok, this is not exactly a power dongle, I wouldn’t choose it to run my planar headphones, but as an option for IEMs, or even some of my easier to drive over ears, it does a very satisfactory job.

The sound is very neutral, with a hint of coolness but without ever seeming to be harsh or bright. When starting to listen to the 71, I grabbed the IE600 (just because I had them at the side of me) with the custom tips and the result was great. There was nothing about the sound of the IE600 that sounded “off” or “wrong”, with the bass being fast and punchy, and the details shining through as they should with these IEMs.

I tried quite a few of the IEMs I had on hand and the 71 performed well with all of them. If I had to pick a negative one, it would be with the Hifiman Svanar, but even then it is not really a negative, just not quite as good as I am used to it being. I have been listening to the Svanar mostly paired with the M15 but I fell in love with it paired with the Cayin N7 lately and swapping to the 71 just took away some of the beauty of the sound of these IEMs. Obviously neither comparison is fair, as the M15 is a 200€ dongle and the N7 is a 2000€ DAP, and it is not like the differences are in any way suggestive of the price differences, but it was a noticeable step down in the overall presentation of these IEMs (which we need to remember are 60 Ohm with 100dB sensitivity, so it is asking quite a lot from the not so powerful 71).

A set of headphones that I like to use on dongles to give me an idea of performance are the Koss KPH40. These cheap headphones are something I have found to show quite a bit of difference between sources, especially portable ones. They never sound “bad” (and with the 71 this stays true) but I do find that the clarity of bass and the presence of air can change quite a bit. With the 7Hz dongle, I did find that some of that clean punch was lost, with the highs not being quite as open and clear as with other options. By this I don’t mean that there is a huge difference, they are still good sounding headphones powered by the 71, just not as exciting as they are from some other dongle options.


The 7Hz 71 dongle is a cheap, ultra portable, dongle DAC that has a surprisingly neutral and present sound. I would not really suggest it for over ear headphones, especially those that are not extremely easy to drive, but with IEMs it is a very good performer for very little money.

I have a bunch of dongles (they seem to be breeding) from different manufacturers and at very different price points, and while I wouldn’t say that the 71 has suddenly beaten them all, I would have absolutely no issue using it, much less recommending it.

If you are looking for a very budget friendly dongle and you don’t need balanced (let’s face it, most of us don’t really need balanced), to pair with a decent set of IEMs, then I think the 71 is a great option. 

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