TOPPING NX2 Ultra Slim Portable Audio Amplifier Headphone Earphone Amplifier, with USB DAC - Reviews
Pros: Size, battery life, VOLUME, sound
Cons: interference, shoddy DAC, usb mini
This is my first review, but I have such a conflicted relationship with this device, I wanted to put it down in words! As this review focusses on use as an amp, I'm not going to use the typical "highs miss lower structure. If you read this you'll see why.

Firstly, this unit was give free to me by in the UK, who had a bit of a service failure with an order of mine, and so (following a joking request from me to customer service) delivered this as a "present" (along with the HD600s I had ordered) . I am in no way affiliated with either Topping or hifiheapdhones (save as a customer) and this review represents my honest opinion. I have received no inducement to write this review.

Kit: I tested the NX2 as a USB DAC/AMP from both a windows laptop, a Samsung Note 8 and Galaxy S8. I have used it with Shure SE215s, 425s, KEF M500s and Sennheiser HD600s. Here's a nice picture... it's tiny!


DAC: after about 10 minutes of using as both a DAC and AMP, I stopped and almost chucked this unit away. Whilst it delivered volume, the sound (using as a dac) was not good. There was a lack of detail, as if the music was far away and veiled, with a muddy/flabby feeling. Honestly, I nearly wrote the unit off there and then. I slung it in my bag and didn’t think anything more of it. I wont even bother with test tracks, highs-mids-lows etc. Trust me, the answer in each column is "awful, just awful".

Redemption: A few weeks passed, and I was working away from my normal office, listening to my music on my 425s direct from my note 8. I have always thought the 425s do better with a little amplification (and my dream pairing had always been my dragonfly until I lost it). I suddenly remembered the NX2 and plugged it in as an amplifier using the 3.5mm male to male it came with (crappy, swapped out for a fiio one i had lying around). And I was seriously pleased with the results. I can't profess to have volume matched, but sticking the NX2 between the phone and the 425s gave them that much wider, fuller feeling sound the 425s reproduce under amplification. Where I really notice it is in soundstage (width) and bass response. Without amplification I think the 425s can be a little shy of bass, but with amplification (including with the NX2) that tight, clean bass they deliver has an extra level of oomph I really enjoy. The first time I ever experienced this degree of clarity from my 425s was after having first bought my dragonfly 1.2 which retailed at about 5 times the cost of this little NX2. I genuinely cannot fault its incredible value for money.

The other headphones I have in the office are the KEF M500s. These get plenty loud from a phone, and so I wasn’t expecting much to change. And it didn’t really – the NX2 drives them louder and there may be a feeling of wider soundstage, but it is negligible. What it does do though, is add clarity. Don’t get me wrong, the M500s don’t have a muffle issue, but I do notice from direct outputs from both the S8 and Note 8, a muffle that amplification seems to clear.

When I got home that night, I also gave my HD600s a bash with it – and you know it does a good job! The phone itself doesn’t drive my HD600s to a nice listening volume for me, but the tiny little NX2 comfortably provided all the noise I needed!

So, a £30 box which delivers ridiculous amplification for such a tiny, compact, convenient unit (crap DAC or no) is a sure fire 5 stars, A++ right? Not quite…

Unfortunately, the NX2 suffers from 2 issues:

Firstly, the battery charging port is USB mini. It is literally the only USB mini device in my house, and I cannot understand why Topping would not simply use the ubiquitous USB micro standard.

Secondly, this unit suffers from massive and unforgivable electronic interference. Given it is marketed as a mobile device, any time it is near a phone, you have (with no music playing) the tell-tale clicking and buzzing of mobile phone interference. Add music playback to the mix, and the ripping/tearing/clicking/popping is unlistenable. This can be noticed when stationary in an area of good signal but makes the device totally unusable on train journeys where the phone is regularly trying to contact the network. This flaw makes the Topping NX2 practically unusable whilst travelling which is (considering how convenient and effective it otherwise is) a real shame.


I love and hate this Topping NX2. As a DAC it is terrible. As a straight amp, its size, convenience and the simply fact it does a great job of what it is there for, give a lot to recommend it for. And I love it for making my 425s sparkle. I could even overlook the nonsensical use of the usb-mini format. But I cannot forgive the RF interference – it makes it, when using a phone as a source (which, lets face it, the vast majority of us will be doing) totally unusable.
Pros: Infinite battery life/power, wider soundstage, extremely small and light, powerful enough for most source
Cons: Interference with smartphone on active data, dampen bass response (muddy bass?), mini USB instead of micro USB

I bought Topping NX2 through Ebay for 42USD. It arrived from China to Malaysia in 3 week which is quite fast considering most of my other shipment from China usually took 4-6 weeks.
As usual they provide accessories like mini USB charger, short 3.5mm male to male jack, 5 pairs of round Velcro and 2 stacking band. First impression; it's housing is smaller than I ever imagined. Pictured above with one of my smartphone Samsung Galaxy S advance (2012) which has 4 inch screen.The housing itself was made with metal. There is some small gap at the top plate. Not more than 0.5mm but still noticeable. The top and bottom plate are secured with 4 screws (with Allen key hole) at both side of housing.
Stacking with Samsung Galaxy S advance using provided rubber band. Top and bottom screws used to secure bottom, top plate. Most likely removable with correct Allen key.
The top side of Topping NX2 matched with bottom side of Samsung Galaxy S advance. This was one of the rarest phone with earphone hole at the bottom together with micro USB charging port. This is my favorite combination for ease of charging and listening to music at the same time. Even better if both earphone hole and micro USB port are located at the top but unfortunately not many phone has this kind of combination.On Topping NX2 top plate there is volume control (0-10). Beside that there are aux in hole and earphone out hole. And at the other corner the is short stick for on and off switch. I call it stick because it is not a button and it protruding about 3mm from top plate. There is blue LED button in between the earphone hole to indicate that Topping NX2 is functioning.
This is my first ever portable amplifier, so I have no idea how it affecting the sound from headphone/earphone. Generally the end effects are; slightly lowered bass quantity with dampened bass response. So the bass somehow sound less impact-ful and some user commented that it sound muddy (what ever it is). Otherwise the other effects are it widen the soundstage making the sound fuller and heavier. Treble and detail are become slightly more prominent . The end effect/summation making overall sound more engaging and even fun. I tried it on my biggest impedence earphone Audio Technica CKB50 (65 ohm) and Topping NX2 can easily drive it to insanely loud volume.
The battery last almost forever (or 100hours as claimed by manufacturer). Even when on charging it can still fully functional. Full charging take about 1 hour.
I tried it on my Acer AIO desktop and old Acer laptop (2007). Both detect Topping NX2 automatically and install the intended driver. All my smartphone has no OTG function so I never tried USB DAC from smartphone.
I have second thought about this whole amplifier thing. While it generally give a whole new sound to my earphones I think it is better to get a player with built in powerful amplifier. This is why I am missing my late Lenovo S930. Most of the time I only use about 10% of the volume and some loud earphone like Soundmagic E10 already sound too loud with lowest volume. Subsequently I bought HTC Desire 820s. Bad mistake, now I use 40-50% of volume to drive most earphone. With AT CKB50 I even have to use up to 60% volume. Topping NX2 did help with this problem but if I have both player and powerful amplifier it will be great. Maybe there is LG V10 :) which will cost me an arm and leg.