Specifications: well they are so many that I suggest going visiting their website. The DAC is the Sabre ES9038Q2M, though.
Thanks to Apos Audio for providing this review sample. They are a great team with a nice customer support and an amazing warranty service (24 months). Also, they sell fantastic products and they usually guarantee the best prices available. And they ship lightning fast, believe me.
Unboxing and first impressions
First thing: the rationality. This box is as big as it needs to be. It’s black (and you know how we love that), it’s elegant, it’s minimal. No information on the box but a Hi-Res sticker. Inside of it, there’s the main character, the NX4, as well as its accessories: a set of cables (Micro USB – Micro USB, Micro USB – USB Type C, Micro USB – USB Type A, jack to jack), two rubber bands to stack it, some pieces of Velcro and an anti-slip piece of rubber which reminds me of the XDUOO XP-2 one. To be honest, this product is somehow similar to that one, and the accessories are too. There are, as well, some papers – aka instruction manuals – even though they are not so necessary due the intuitiveness of this device.
The device itself is handsome, with a matte black finish, a great build quality and an amazing design. It has rounded corners, solid switches and the volume knob has a good feedback (the first “click” turns on the device). The switches are two: one for the bass booster, another for the gain. There are two 3.5mm jacks on the front: the left one is for your headphones, the right one is for a line input. The back has two micro USB (one to charge and one to connect via USB). Nothing else. This device has no wireless connection (that’s the main difference compared to the XP-2), so there’s no need to have a switcher. If you connect both the USB and a line input device, this last one will have priority.
This device supports native DSD. I used Audirvana on my MacBook Pro which lets me choose the NX4 as output device (note that when you choose it on Audirvana, the system settings won’t let you use the NX4 for other applications, and vice-versa). On my Xiaomi Mi MIX 2 I used Onkyo HF Player Premium with OTG support to support DSD; even if the device itself recognize the NX4 as output device, the default music app won’t reproduce DSD and even other applications would convert it to reproduce such files. However, I’m not the most assiduous DSD user, because they are pricy files or supports (SACD) and they are very heavy on the storage side, while the sound quality is not crazily improved by the human hearing possibilities, by comparing it to the best FLACs. Also, my phone does not support micro SD expansion, so I’d rather use a DAP to have a portable device. But I have to say an important thing: the DSF file of Bohemian Rhapsody via this NX4 is the only one I have which doesn’t crack on the guitar solo, and I tried all files from all sources with all my earphones before. So, this device is actually the best DAC/Amp I have, at least for reproducing that particular track which is not gentle with gear. The NX4 works flawlessly as a desktop DAC/Amp with my Mac and has no issues at all even with my smartphone. Speaking of DAC+Amp, the device gives its best when used this way. You can also use it just as an Amp, but the output volume will be lower – the battery, on the other hand, will last longer. An amazing feature is that I can use it as a DAC even with my FiiO M7 (the XP-2 doesn’t work this way) and the combo is absolutely amazing. I was afraid it wouldn’t have worked, but it actually does and gives a great mobile experience. This portable setup is better than ever for my use, because I have my library inside the FiiO – my phone doesn’t have so many albums inside because it doesn’t have storage expansion capabilities.
I mostly use IEMs, so most of the times I don’t need to use high gain on my sources. However, something like the Tin HiFi P1 needs a lot of juice to sound as its best and here’s the case too (I actually can go at maximum volume with those planars!). To avoid turning the volume up too much, with classic earphones, the high gain switch gives a consistent boost to the output volume. I also turned it on to use my Sennheiser Momentum On ear, even though they are pretty moderate on the driveability side; they won’t distort when you pump it a little bit more than necessary, so it’s nice to have a strong output for those.
Unlikely the iFi xDSD, the NX4 really gives a boost to the bass with this mode turned on. Something like the already mentioned Tin P1, whose bass is pretty soft, will sound as their absolute maximum capabilities with both switches activated. I really like when the switches are functional and useful – yes, I’m very critic about the super overrated xDSD by iFi which has ridiculous switches for stage virtualization and bass boosting which actually almost make no difference.
Sound and comparisons
Among the XP-2, the NX4 and the xDSD, the TOPPING contender is my favorite. While XDUOO (100$) and iFi (450€) provide wireless capabilities, TOPPING focuses on maximizing the wired performances on their NX4, a product that shines in every aspect. Its design, its easiness of use, its honest use of input ports are features that put it over the other two: no useless LEDs, no stupid colors which cannot be seen by colorblind people like me. The NX4 is a machine that’s suitable for everyone who needs a DAC/Amp which is perfect both for desktop and mobile use. While the Bluetooth function could have been a plus, I believe that’s a choice they’ve made to keep the final price lower – that’s also why they put micro USB ports instead of USB type C ones.
As I’ve already said, I’ve been really surprised to find out this device is the only one which can reproduce “Bohemian Rhapsody” without distortion on the guitar solo. Ergo, this device can handle the most difficult tasks better than my Focusrite 2i2, my XDUOO XP-2, the FiiO M7 and the iFi xDSD (yes, this one too), as well as my phone and other occasional devices I’ve tried. It may be also due the DSD file, which for the first time I’ve understood the sense of. It is actually better than a classic FLAC24 and obviously better than MP3 and MQA too. But if you have a good master (and previous steps), I still believe it’s not necessary to have a super heavy DSD (DXD, DSF, ecc..) file.
Let’s rank the three devices I’ve mentioned earlier. The XP-2 is a great analytical device, with a flat signature and a nice attention to details. I prefer it over the xDSD because the iteration by iFi tends to heavily color the sound, giving a good listening experience (and a very powerful output) but nothing I would call reference. The TOPPING NX4 is something I would put in the middle. It is less colored than the xDSD, but its bass booster can give more character to the low end without sacrificing a flat nature. There’s a great detail on the NX4, and it sounds more lively than the XP-2, which is also less powerful. Generally, I find the TOPPING product capable of pushing on the extreme frequencies more than the XP-2, without any doubt or distortion. It’s true that the price is higher and this would be to expect, but well… It works as predicted. Sound-wise it is my favorite device of its kind (I’m obviously comparing all of them to the lowest common denominator, so as wired DAC/Amps).
Actually, my NX4 is stacked with my FiiO M7 and this match is so wonderful that I don’t feel the need of upgrading my mobile setup. But I believe the output wouldn’t be enough powerful for some kind of headphones, since it sometimes struggles even with the in-ear planars by Tin Audio (if you just use the NX4 as an Amp).
The battery life is great, I can use it via USB for more than 6 hours, while the Amp mode can grant me so much time that I’ve lost count. I mostly use it as DAC too, though.
I’m enthusiastic about the NX4. This is the first product by TOPPING that I try and I honestly understand why it is so appreciated as a brand. Not only a great build quality and design, but also a versatile product for both portable and desktop use and compatible with FiiO products (not granted as XDUOO does not support them). I love this device and it actually is one of my favorite pieces of gear. For the price, the audio quality is outstanding, the accessories cover every device you may need (for iDevices I think it’s necessary a camera adapter by Apple) and if you buy it from Apos Audio, you’ll have an amazing customer service as well as a second year of warranty. Oh, and if you don’t like it – I strongly doubt – you have one entire month to return it. Absolutely recommended.
Design and build quality
Output power could be not enough for headphones and planar IEMs