Dobrescu George

Reviewer: AudiophileHeaven
Pros: + Build quality
+ Clean aesthetics
+ High damping factor, leads to a unique sound and presentation
+ Good battery life
+ No EMI when using it
Cons: - Hard to stack physically
- Pricey
- If the source isn't ideal, it amplifies the source's noise floor as well
Uber Nano Mini - Periodic Audio Nickel AMP Review

Periodic Audio Nickel is a unique device of its own, a high-power mini mini Amplifier that's the size of a dime. For its 300 USD price point, it has quite a few other amplifiers it has to beat before it has a place of its own, like iFi xCan, Burson Playmate, and even DAPs like FiiO M9.


Periodic Audio is a well-known company from USA, having designed and created some really interesting IEMs in the past, all of which I've reviewed here on Audiophile-Heaven. The main feature of Periodic Audio so far has been to define their products by a specific chemical element that each product is based on, for example the previously released Beryllium, Titanium and Magnesium. The IEMs from Periodic Audio have always been interesting, not just because they've been amazing by themselves, but because Periodic Audio managed to design very basic looking IEMs that still had good reliability and excellent sonic performance. This being said, their products aren't exactly the least pricey, but, Periodic Audio provides excellent support and after-market service, so you don't need to worry, as they'll have your back, if you decide to purchase something from them.

It should be noted that I have absolutely no affiliation with Periodic Audio. I'd like to thank Periodic Audio for providing the sample for this review. This review reflects my personal experience with Periodic Audio Nickel, also named Periodic Audio Ni throughout this review. Every opinion expressed is mine and I stand by it, the purpose of this review is to help those interested in Periodic Audio Nickel find their next music companion.

About me


First things first, let's get the packaging out of the way:

The package of Periodic Audio Nickel is very basic, but inside you can find a good number of extra cables, including a line cable, and a charging cable for the little Nickel. There's not much else in the package, but I love the design and the information written on it, and you'll have a fun time reading a bit through it and learning more about Nickel and the properties of this tiny device, some of which are quite amazing.

What to look in when purchasing a portable Amplifier

Technical Specifications

Build Quality/Aesthetics/Functionality

Nickel is one of the tiniest Headphone Amplifiers that has ever been made, but despite its mini size, it is one of the best balanced physically, and despite the entire case being made of some kind of plastic, it feels good to the touch. There is one headphone input, one headphone output, one microUSB charging port, and one battery LED indicator. Nothing else on the surface of Nickel, so not much to talk about here. The 20 grams weight of the nickel makes it the lightest Amplifier on the market at the moment of writing this review.

My two notes about its build quality are that it doesn't get very hot during usage, instead staying pretty cool most of the time, and that it doesn't scratch easily, so you can safely take it with you and use it anywhere you need.

Now, you may be wondering why you're not seeing any buttons, and well, that's because instead of having a physical on/off switch, Periodic Audio embedded a sensor in the Nickel, so it only turns on when both the input and the output 3.5mm headphone ports are populated. This means less headache for you, and more battery saving magic, also for you. The battery life of the little Nickel is stated to be somewhere around 8 hours, and well, for a device that always runs at maximum power, it is somewhere around that. With a charging time of just 30 minutes, you probably won't feel that the battery is short any moment soon.

You can charge Nickel while listening, and the fact you're charging it will not break your sound quality, and won't affect it in the least.

The body shape and functionality are so basic that there's hardly more to talk about, but if you were wondering how easy it would be to stack it, if you get slimmer cables, you could use a double sided tape, or some velcro to strap it to your source, and it becomes a very portable and nimble little device. Of course, if you were looking for something slimmer to stick to your smartphone, then you're better off using a longer line cable and leaving Nickel in your pocket, or using it connected to something like a FiiO Bluetooth Module, to give it more power.


Sound Quality

The sound of the little Nickel is mainly described not by how colored it is, but by how much the large damping factor influences every headphone it powers. Basically, having a high damping factor means that all music played through it sounds more cohesive, it has more space to breathe and more nuance, and it has more impact and just sounds smoother, despite having the same amount of extension in both the bass and the treble.

Adding the fact that a device this tiny can pump 250mW into 32 OHMs, and that it can also be used with IEMs that are multi-BA, and which are of the lowest impedance, without making them sound thin, as the output impedance of the little Nickel is quite low. With almost 500 mW per channel pushed in a 8 Ohm load, you get one of the strongest tiny Amplifiers in existence, and a lot of impact and dynamics.

The bass of the little nickel can be described as very coherent and liquid, and one thing you wouldn't expect from this tiny one, is how hard and deep it hits, even with headphones that are slightly harder to drive, like the Sennheiser Signature DXP, or the Verum One that also appears in the pairing section of this review.

The midrange also has that magical liquidity and cohesiveness that the bass has, and here you can hear what a high damping factor does to sound, it simply gives everything a magical smoothness, and makes every single headphone and IEM it comes in contact with more musical, and gives them a free flow from each musical note to the next. The soundstage of this little AMP isn't that large by itself, but as its characteristic sound gives every musical note more air to breathe, resulting in a really good overall imaging and depth, making the entire stage quite well-rounded and giving instruments air to breathe.

The treble feels well-extended and has a good amount of sparkle, but once again, the smoothness of the little Nickel sticks with me in a magical way, as it feels like it takes away all harshness if your source or your headphones used to be harsh, taking the sibilance away as well.

Overall, that high damping factor works like a charm, if you want your headphones and IEMs to sound smoother, but please be aware, while this creates a very clear sound, it takes some of the analytical properties away, and if you're a fan of textures, having a high damping factor may rain a bit on your parade, the sound of the Nickel is quite musical and enjoyable, but it is not a very textured sound.


Portable usage

In terms of portable usage, with a pretty strong battery life that will outlast or live as long as most portables, and with a weight of just 20 grams, and a tiny body, the little Nickel is one of the most portable Amplifiers in the market today. The fact that it also has a basic body shape, and doesn't require any special connectors to work, means that you can use any line cables you had lying around without having to purchase anything especially for it.

Furthermore, Nickel works while charging, so if you go on a longer trip, you can also connect a power bank to it, and it won't degrade the sound, but it will keep the power flowing and the music going. Nickel doesn't pick up on Interference from smartphones, so you can keep enjoying it even while on-the-go, and even if you have it strapped on to your smartphone.


The main competitors chosen for this review are iFi xCan, Burson Playmate, and FiiO M9, all of them different from the little nickel, and basically chosen based on their price points rather than based on their shape and design, as I never reviewed a device that was this tiny before.

Periodic Audio Nickel vs iFi xCan (300 USD vs 300 USD) - Starting with a pretty interesting comparison, you may be thinking that the only thing the little Nickel has to offer above xCan, taking into account that they are at the same price, is that the Nickel has the smaller size and it is more portable. But, on a closer look, the tiny nickel has just a slightly lower battery life, it has a similar driving power, and, although it doesn't have all of the bells and whistles of the xCan, like the Bluetooth DAC, and the special effects, the unique sound of the little Nickel still makes it an interesting choice, if you wanted an amplifier with a huge damping factor, that will make your headphones and IEMs smoother, will keep their extension in the treble, but smooth out their textures, and if you wanted something to increase the punch and dynamics, compared to your source, but if you didn't want to take a larger device, like the xCan.

Periodic Audio Nickel vs Burson Playmate (300 USD vs 400 USD) - Burson Playmate is quite a bit more expensive than the tiny Nickel, and we're actually comparing a full Class A desktop headphone amplifier with a tiny portable microAmplifier here, but since their price points was close enough, I thought I'd also show what else the same amount of money could get you. Playmate has a ton more features, including a line out, and a DAC inside, but when it comes to its sound and driving power, Playmate also offers 8 times the driving power of the little Nickel. This being said, the sound is quite different, and if you're in need of a portable, the little nickel provides a higher damping factor, and a smoother overall sound that will make even the most harsh and analytic headphone sound smooth and musical, and the little Nickel also has the form and shape to its advantage, with Playmate needing a power converter to work at all times.

Periodic Audio Nickel vs FiiO M9 (300 USD vs 300 USD) - FiiO's M9 is actually priced at the same price point as Nickel, and again, the point here is to show what else the same money can get you, as you may be wondering if it is worth to invest in the little Nickel, with so many interesting audio devices on the market at this moment. FiiO's M9 is a full blown DAP, with a microSD card, and even with Balanced Outputs, having way too many features to spend time comparing it to the little nickel. If you push M9 to its limit, it has a similar battery life compared to the little Nickel, and this makes the mini Amp in the question quite interesting. When it comes to the driving power, you could actually add Nickel to M9 to get a bit more impact and driving power, and you would also get the smoother, more musical sound that Nickel has when pairing it with FiiO's versatile DAP.


For the pairing part of this review, I have chosen Periodic Audio Be, Verum One, and HIFIMAN RE2000 Silver IEMs.

Periodic Audio Nickel + Periodic Audio Be IEMs - As many others have pointed out, the pairing with Periodic Audio's own BE IEMs is one of the sweetest out there. For those who wanted to see this already musical and magical sounding IEM become even more musical, this is just the thing, as the little Nickel gives them an even smoother midrange, takes away even the last bit of harshness and sibilance from their treble, but leaves the sparkle there, and gives the, a very well separated, large sound.

Periodic Audio Nickel + Verum One Headphones - Verum one is one of the smoother, more musical headphones by default, and it is also one that's a bit more complicated to drive, not because it has a high impedance, or because it has a low efficiency, but because it has a very low impedance, and if you want to make them loud, they will drive your amplifier into overdrive. This test was more about testing whether the little nickel enters overdrive easily, or if it can drive very low impedance loads. The thing here is, when something has a very low impedance, for the amplifier, it is almost like connecting its poles to each other, which can easily short an amplifier, leading it to overdrive and making it shut down. It sounds quite horrific when it happens, and those of you who have speakers may know that really low impedance speakers are much more complicated to handle than high impedance, high efficiency ones. Back to the little Nickel and this pairing, Verum One was already plenty musical, and plenty thick, so the little Nickel doesn't change its main signature quite that much, but I can say that if you're trying to power Verum One from a smartphone, or a source that's struggling, the little Nickel will help Verum One gain better impact, better control and a more dynamic sound, leading to a much more pleasing overall experience.

Periodic Audio Nickel + HIFIMAN RE2000 Silver IEMs - RE2000 Silver from HIFIMAN is one IEM that you'll quickly fall in love with, if you're into analytic and precise sound, and if you like to hear every texture, but despite what you may expect, pairing the little Nickel with RE2000 Silver doesn't result in a bad sound, and actually is quite pleasing. The resulting sound is smooth, but detailed, clear but not harsh, and it has a good amount of detail, despite being very fluid. The speed of RE2000 is still there, and their instrument separation didn't decrease, but actually improved, leading to a pairing that you can enjoy for hours, especially if you felt that the original signature of RE2000 Silver was a touch harsh.

Value and Conclusion

The value of the little Nickel is a slightly complicated topic to talk about, as it is a slightly expensive device, priced at 300 USD, and it is a very specific one at that. If you want the kind of sound it provides, then very few other devices on Today's market will provide that sound, especially in this mini, convenient shape. On the other hand, if you're just looking for a typical headphone amplifier, and you don't care about the size / shape and if you just need the power, then the price probably won't make the most sense to you.

Starting with the package, you get everything that's basically needed to operate the little Nickel, a Line cable, a USB Charging cable, and that's pretty much it. You will need to purchase a solution for strapping it to your smartphone, and longer / shorter cables if you won't like the length of the ones included by default.

The build quality is pretty much indestructible, and the tiny Periodic Audio Nickel is made to last a lifetime, with a minimalistic shape and design that you simply can't break and aren't likely to scratch. It also saves you the headache of forgetting it turned on, having a sensor that only starts it when both the input and the output cables are connected, but also having a little LED indicator that tells if when it is turned on and how much battery is left.

The sound is unique, powerful, and sublime, especially if you were looking for something that will smooth out your music, having a pretty high damping factor for music, turning almost any IEM and headphone into a very musical one. The power driving factor is amazingly good as well, and for a device this tiny, you'd be hard pressed to find anything that can push the dynamics and punch that this little fighter has.

At the end of this review, if you're looking for a mini AMP, something so tiny that you won't even notice it, and if you're looking for an amplifier that increases the musicality, smoothness, and overall coherency of your headphones or IEMs, then the tiny Periodic Audio Nickel makes a very good proposal, and don't worry, despite its mini size, it has the roar of a monster, from the size of a mouse.

Full Playlist used for this review

While we listened to considerably more songs than those named in this playlist, those are excellent for identifying certain aspects of the sound, like PRaT, Texturization, Detail, Resolution, Dynamics, Impact, and overall tonality. We recommend trying most of the songs from this playlist, especially if you're searching for new most, most of them being rather catchy.

Youtube Playlist

Tidal Playlist

Song List

Bats - Gamma Ray Burst: Second Date
Eskimo Callboy - Frances
Incubus - Summer Romance
Electric Six - Dager! High Voltage
Kishida Cult - High School Of The Dead
Dimmu Borgir - Dimmu Borgir
Breaking Benjamin - I Will Not Bow
Thousand Foot Krutch - The Flame In All Of Us
Gorillaz - Feel Good Inc.
Infected Mushroom - Song Pong
Attack Attack - Kissed A Girl
Doctor P - Bulletproof
Maximum The Hormone - Rock n Roll Chainsaw
Rob Zombie - Werewolf, Baby!
Escape The Fate - Gorgeous Nightmare
SOAD - Chop Suey
Ken Ashcorp - Absolute Territory
Machinae Supremacy - Need For Steve
Ozzy Osbourne - I Don't Wanna Stop
Crow'sclaw - Loudness War
Eminem - Rap God
Stromae - Humain À L'eau
Sonata Arctica - My Selene
Justin Timberlake - Sexy Back
Metallica - Fuel
Veil Of Maya - Unbreakable
Masa Works - Golden Japang
REOL - Luvoratorrrrry
Dope - Addiction
Korn - Word Up!
Papa Roach - ... To be Loved
Fever The Ghost - Source
Fall Out Boy - Immortals
Green Day - Know The Enemy
Mindless Self Indulgence - London Bridge
A static Lullaby - Toxic
Royal Republic - Addictive
Astronautalis - The River, The Woods
We Came As Romans - My Love
Skillet - What I Believe
Man With A Mission - Smells Like Teen Spirit
Yasuda Rei - Mirror
Mojo Juju - Must Be Desire
Falling Up - Falling In Love
Manafest - Retro Love
Rodrigo Y Grabriela - Paris
Zomboy - Lights Out
Muse - Resistance
T.A.T.U & Rammstein - Mosaku
Grey Daze - Anything, Anything
Katy Perry - Who Am I Living For
Maroon 5 - Lucky Strike
Machinae Supremacy - Killer Instinct
Pendulum - Propane Nightmares
Sirenia - Lithium And A Lover
Saving Abel - Addicted
Hollywood Undead - Levitate
The Offspring - Special Delivery
Escape The Fate - Smooth
Samsara Blues Experiment - One With The Universe
Dope - Rebel Yell
Crazy Town - Butterfly
Silverstein - My Heroine
Memphis May Fire - Not Over Yet

I hope my review is helpful to you!


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Great review, no problems at all driving the Verum? I assume it was a Mk I? Thanks.
Dobrescu George
Dobrescu George
@sl418 - Yep, it was a verum 1, the pairing was fine, made them smoother and more musical thanks to its high damping factor


Headphoneus Supremus
Pros: small, easy to use, plenty of power, good sound quality
Cons: price, no dac, reliance on 3.5mm jack
I was sent a nickel direct from periodic audio in exchange for my opinions. The unit is mine to keep, but these are my honest opinions. The unit sent to me is also one of their "blemished" versions, so certain thoughts about the build or aesthetics of the unit will reflect that.

About Me:
I have been in this hobby on and off for a number of years now, much more seriously into it recently with a heavy focus on IEMs and portable listening. I am mostly interested in the IEMs themselves and dont put a huge amount of stock into other components really making a large difference in terms of sound quality. I see an hear lots of talk about cables and amps all making these massive improvements, and its just not something I have personally experienced or really put much stock into. And its from that perspective that I approached this item.

About the Nickel:
The nickel is a small headphone amp that retails for $299, or $199 for a blemished version.

Some of the important specs from the periodic website about the nickel:
  • THD+N: < 0.005%, 20 Hz to 20 kHz
  • Gain: 6.5dB
  • Power Output: 250 mW Continuous, 32 Ohms
  • Damping Factor: > 100 @ 32 Ohms
While I am not the most studied up on specs and how they affect things. This should be more than enough power to power most headphones thrown at it with the exception of some of the much harder to power headphones.

The unit itself is about the size of a 9 volt battery. Its very small and very portable. Included it comes with a short usb cable for charging and a male to male 3.5 cable to send audio from your source to the nickel. The body is plastic (polycarbonate) and feels solid enough. My particular unit, the connectors (and feels like all the internals) are slightly loose. I can wiggle the usb connection and feel the jacks moving on the other side. However, as mentioned above, this is a blemished unit, and I would expect this not to be an issue on a normal unit, even though I barely register it as an issue now.

The packaging is a relatively plain white box. It is pretty sparse and definitely is not going to satisfy anyone who is into the whole unboxing experience. Here the box is definitely just for packaging and thats all. If you are expecting a fun unboxing experience, look elsewhere.

In Use:
The nickel is extremely easy to use. Plug the cable from your source into the nickel, plug your headphones into the nickel and... listen. Thats it. The nickel automatically senses when both plugs are being used to power itself on. There is no power buttons to mess around with, no volume, no gain switches, none of it. Its plug an play in the best sense of the word. Volume control remains with your source device. There is an indicator light that shows battery levels that also doubles as the charging indicator too.

The 3.5 jacks are extra strong so it may take some extra force to get your cables inserted, but I have read that this was done on purpose with the intent that they are strong enough to support the nickel hanging from your device. In theory thats great, as the nickel itself is lightweight. And while the jacks wont be the source of failure due to their strong lock, if you are using cables that cant hold up, that could potentially be an issue.


Overall, its a slick little package that is very portable and super easy to use. The markings could potentially be a little more clear as to which jack is which. It is fairly obvious that the triangle pointing inwards is the input, while the triangle pointing out is for the headphones. But I could see it getting easily mixed up.

One caveat to the usage though. The order of plugging in the headphones and the input cable are important. Likely it will not do any damage, but if your headphones are plugged in first, plugging and unplugging the input cable can create a loud popping noise that can be very unpleasant.


It does make for a slick little package, especially with periodics IEMs. Slap in a small case like this and you have a nice solution for great quality portable audio.

Sound Quality:
This is likely the most important part and it is a part that I may not necessarily be the best person to review. As stated above, I think most of the quality comes from the headphones themselves with other components only contributing a small amount. And I do not think there are ever really large gains to be had by swapping amps and dacs and all that, unless of course the dac is bad, and the headphones are underpowered.

Of course, for small sensitive IEMs, I think its unlikely that they will be underpowered. However, phones are often not created with audio quality as a priority, so I do think there is likely room for improvement there. And that is exactly what this product is targeted at, phone users who want a little more quality without having to carry around large extra gear.

The nickel is however only an amp. So if your phone has a poor dac already, it will not be able to improve on that, but only on the amp section.

For me, I use a oneplus 5t. It is adequate with its audio output. And when I use my IEMs directly from my phone, its fine. Likely not the best audio quality but more often than not good enough.

And so while I am dubious about the effects of a device like this, I definitely could hear a difference between it and when just using my phone. The sound is ever so slightly cleaner and more detailed with better dynamics. Its not a night and day difference, but the difference is there and it is noticeable.

One major flaw:
The flaw here is not with the device itself. It does exactly what it promises and does it well. And it does it in a really slick, really small and really portable package.

But, in 2019, and likely as we move in to 2020 and continue forward, phones are increasingly not coming with a headphone jack anymore. So I am left wondering exactly who this product is targeting. Those with phones who dont have a headphone jack already have to use a dongle of some sort to use wired headphones. This would just then essentially be a second dongle. And I cant see that being very popular. There are also already some great and very portable usb dacs out there that provide enough power for most portable headphones and IEMs. While the nickel would still likely provide an improvement, I imagine it would be very small.

And for those that use a dedicated dap, chances are the dap itself is already geared in some way towards audio quality. And adding a separate amp might be redundant or again would present very small improvements.

Then there is the price. $299 is not a huge amount in the grand scheme of audio gear, but it does feel like kind of a lot. Even the $199 price for the blemished still feels like a lot for such a portable amp, regardless of the technology included. Perhaps if the device had a built in dac and could plug directly into the usb or lightning port of your phone it could certainly be billed as a higher quality dongle than normal.

So, it took me a while to really come to terms with this and how I would rate it. It definitely achieves its goal and does it in a really small and slick package that is super easy to use.

But for the price and with phones increasingly losing the 3.5 jack, this is just hard for me to recommend unless it meets your sort of exact specific needs.
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New Head-Fier
Pros: Clean Power, Small size, Good damping factor, Made in the USA (Kindof or a pro?)
Cons: Noisefloor is audible across all sources and headphones, Finishing on the chassis, Limited accessories
Dan from Periodic Audio has graciously sent me a review unit of the C and the Nickel amplifier for honest reviews. This review is in no way sponsored and I will be honest about my feelings surrounding this product. . This is my humble opinion. YMMV!

Here is a link to my review on the Periodic Audio Carbon's (for those who have not read it).


"Blah Blah Blah". This is my third time going down this path. I'll let my previous reviews do the talking. Instead, here is a throwback photo to Canjam Singapore 2018 where I met Dan from Periodic Audio for the first time:


The Nickel is the start of Periodic Audio's foray into digital electronics. Being their first portable amplifier, Dan and his team made sure to fine-tune and improve upon existing prototypes, with feedback from consumers at headphone meets and annual CanJams across the globe. Priced at $299 USD, the Ni is an accessible piece of porta-gear that complements any audio setup.


Capture 1.JPG
Capture 2.JPG



In an effort to save time, I'll spare you the details on the packaging. It is exactly the same as their IEM counterparts. The point of departure starts with the box's contents.

1 X Periodic Audio Nickel
1 X 3.5mm to 3.5mm Interconnect (Short)
1 X Microusb to USB Charger (Short)

The Nickel's offerings are a little sparse. It would've been nice if Periodic Audio had included rubber bands for a transport-amp stack. It comes as no surprise that Periodic Audio only includes what is necessary, with reference to their IEM siblings.

Design, Build and Function:


Loo and behold! It is a tiny black box. Nothing much can be said. Let the image do the talking. I'll spare you the verbose word-dump.

Adopting a design language as ubiquitous as eating toast for breakfast, all Periodic Audio products are plain jane in the best possible way.

The most important aspect of the Ni is its chassis. Both the electronics and its outer-shell are machined and sourced from American components. God bless America (tough luck, Shinola). The poly-carbonate chassis feels sturdy and tough enough to weather any storms. The size of the amplifier itself measures to be around 2-3 triple A batteries (I refused to conform to the metric system).

If space is a constraint, the Ni shouldn't take up too much real estate. My only complaint pertains to the blemishes on the Ni. The $299 USD price tag warrants better quality control. However, these cosmetic defects may be unique to the set I received and they do not hinder product performance.

The aux in's and out's are marked with large white arrows above them in order to differentiate them from each other. Its design language is foolproof. There are no physical buttons to operate. Instead, the Ni switches on when both aux's are connected appropriately. The green LED at the front lights up during the boot-up process. A yellow LED indicates that battery is running out of juice.

I have brought them out for several test runs and I can confirm that it works well as an on-the-go solution. I wouldn't recommend anyone to use it as a dongle. As a precaution, store the Ni in a separate pocket if you wish to daisy chain it to your source.

Another quirk that the Ni boasts is the fact that it doesn't accept or feed a line-signal from either a smartphone or a DAP (Digital Audio Player). Instead, the Aux-in is wired to a 10kOhm resistor, effectively turning your transport into a pre-amp.

Dan and his team at Periodic Audio make the argument that modern day DACs' in smartphones do not need to be replaced. The reason why headphones sound disjointed on smartphones has to do with inferior op-amps and poor circuitry (high THD etc). With that philosophy in mind, the team created the Ni; a testament to their collective beliefs. It takes the collective minds of mad scientists to concoct such a revolutionary idea.


The Ni has a battery life of 8 hours, contrary to its small size. Taking approximately than 30 minutes for a full charge, the Ni is the perfect companion for the office and the train ride home. The standout feature to me, is its ability to play and charge simultaneously (useful for a clutz like me who regularly forgets to charge my devices).


Don't leave, it's my fault

Tyler the Creator: EARFQUAKE

Now to many, this may be a 'controversial" segment. I do not sit in the camp of "amplifiers can make enormous changes to a IEM/Headphone's sound signature". Instead of waffling between stances, I'll say that I'm a firm believer that any changes made to the audio chain from source to transducer will result in real-world "audible changes". However, I will remain cautious so as to not "overrate" the capabilities of the Ni. After all, what matters the most are the transducers in each headphone/IEM.

Essentially, the functions of an amplifier can be surmised as such; to boost the audio signal to an audible level. It may sound simple in practice, but there are many potential hindrances along the way, not limited to harmonic distortion, noise and clipping.


In the first few hours of using this tiny device, the first thing I noticed is a faint hiss in the background across all my headphones (from the Campfire Audio Cascades to the Hifiman HE400I). In theory, the 10kOhm resistor should eliminate any unwanted background noise from double-amping with the source's built in amp. Unfortunately, the real-world results differ on this front. If you're planning to use the Ni in noisier surroundings, the hiss is unlikely to be picked up on.

Across the board, the Periodic Ni powers all my headphones/IEMs' with ease. The most "power-hungry" headphone I own is the Hifiman HE400I (35 Ohms, 92 dB). For a planar magnetic headphone, it is considered by the community to be highly efficient. From the Campfire Audio Cascades (38 Ohms, 100dB SPL/mW) to the Periodic Audio Carbon (32 Ohms, 98dB SPL/mW), the Ni serves to enhance, not to change the sonic characteristics of each product.

Across the board, the biggest improvement I could identify is how spatial cues sound less congested or closeted. With its enormous 250 mW power output (into a 32 ohm load), bass response is tightened substantially. Each driver attacks and decays at an accelerated rate. Everything sounds cleaner. I'm guessing these improvements are the result of its ultra-low THD (Total Harmonic Distortion) and high current output

Tyler the Creator's Earfquake is a track with unhinged sub-bass rumble. The Campfire Audio Cascade's penchant for ultra-low vibrato is ameliorated by the Ni's excellent damping factor. The mids are clearer, less hazy and brought forward in the mix. If I had to quantify the noticeable improvements, I would say that there is a 25% improvement; an impressive feat.


Their entry into the portable-audio space has proven to be a success. The Ni's touted power output and its non-descript looks are sure to capture the attention of "utilitarian" audiophiles. With its unique design quirks and its distinct "conspicuousness", the Ni is an animal that adapts well to any audio setup.

You'll be hard pressed to find any alternatives to this stellar amplifier.

Make no mistake; this little powerhouse punches way above its price point.

To purchase the product, visit:

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Headphoneus Supremus
Pros: Small size and light weight - Decent battery life backed by impressively quick charging (20-30 mins) - Uncolored signature - Quality components were used
Cons: Very picky about source when using sensitive iems - Lack of accessories - Price (maybe...I understand why it is as it is, it just feels too high)

Today we're checking out the Nickel [Ni], a tiny portable amplifier from Period Audio.

Periodic Audio was founded in 2016 by a small group of audio enthusiasts/specialists with over 140 years of combined experience in the industry. Their aim? To provide accessible, high performance audio products that focus on portability, sound, and comfort, not glitz and glamour.

While it isn't much of a looker, the Ni is packed with tech resulting in a very compact, powerful amp that can easily travel with you during the day. While it is light on features, those that are included make it a very convenient product to use along with your other every day carries.

Let's dive in and take a closer look.


Thanks to Dan with Periodic Audio for asking if I would be interested in checking out the Nickel. It looked like an interesting product from the product information that has been released at the time, so I accepted and a sample was sent for review. The thoughts within this review are my subjective opinions based on around a month of use. They do not represent Periodic Audio or any other entity. At the time of writing the Nickel retailed for 299.00 USD. You can check it out here on their site:

**Note that this is a b-stock unit. It functions fine but has physical blemishes. Expect a-stock units to be cleaner than the one shown here.**

What I'm looking for:

When it comes to portable amps and DAPs I take a pretty casual approach. If you're looking for an in-depth look at this thing with measurement graphs going over THD, sinewaves, etc. you'll want to look elsewhere. All I really care about is how easy is it to use? Is it well built and will it be durable long term? How's the driving power and overall sound quality? Are the batteries going to run dry part way through a listening session? Is this the kind of device I'm going to take with me everywhere, or it is better suited to listening in the privacy of my home?



Full specifications and measurements can be found on the product page (link in 'Disclaimer'). I recommend visiting it if you like graphs.

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Packaging and Accessories:

The Ni arrives in some neat environmentally friendly, cardboard packaging. On the front is a wireframe-style image of the Ni and the components that make it up. In the top right is the Periodic Audio logo, and the bottom left the Ni log as seen on a periodic table of the elements. Opening the top flap reveals a couple graphs, one for THD and the other showing the gain, along with a list of specifications and some product information. Around the sides of the package are black and white macro images of on of their earphones as well as some additional branding. The back contains more information about the Nickel.

Opening the side flap which requires quite a bit of force thanks to the strong double-sided tape, there is a second cardboard box that is free of any branded or logos. Inside is the Ni tucked tightly into a cardboard cutout. The only included accessories, a 3.5mm aux cable and microUSB cable, are lightly draped into a second cutout. In all you get:
  • Nickel amplifier
  • 3.5mm aux cable
  • microUSB cable
Overall a solid unboxing experience. I appreciate that they included measurements with clear axis labels and none of the stylized flourishes you usually see when they are included on packaging. Periodic Audio provides a lot of useful information about features and components too, versus the marketing fluff that is more common in the industry. It would have been nice to receive some additional accessories given the price, such as a carrying case for the amp and cables. Maybe a few different aux cables of varying lengths or with jacks of varied styles (ex. 90 degree, 45 degree, and straight) to ensure you get something that is ideal for your portable setup. Other amps include rubber bands to strap the device to your source. Some of those sized to fit the Ni would have been sweet since none of my existing bands fit. Or maybe some Velcro tabs instead. Anything extra would have been nice and helped make this package a better value.

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Build and Components:

The Ni has a rugged, polycarbonate shell. The only flourishes breaking up what is otherwise a matte black brick are the white painted Periodic Audio logo and arrows above the input/output jacks. When I took mine out of the packaging, there was a a dusting of what looked to be dried glue or paint smattering the top. While it was easily wiped off with a damp finger, I also saw prominent seams between the two main component parts that made up the shell, along with globs of white glue poking out between those seems. I'll be honest, it looks more like a prototype than a finished product, though being a b-stock unit I was expecting it to be less than perfect. That said, even were this not a b-stock unit the Ni visually is not particularly impressive. It's too simple in design for that. It does feel extremely tough though with no flex or give anywhere when squeezing it. Can't say the same for the metal bodied Xduoo Nano D3 I reviewed a while back. Fit around the important parts, namely the 3.5mm in and outputs, the LED light, and the microUSB slot in the back, is tight leaving no room for play. These somewhat delicate components are well protected.

When it comes to components, that is where the Ni's seemingly high price tag comes in. Periodic Audio clearly put a lot of thought into what was going to go into the Ni. First off, it uses a brand new Texas Instruments INA1620 chip. This chip can output 140 mA, continuous per channel, and carries along the Ni's theme of being tiny and portable. This chip is apparently so small they were able to cram it and some other bits and bobbles into the space between the input and output ports. Powering the amp and the amp alone is another piece of Texas Instruments tech, the TPS65133 power controller which results in a low noise floor. A 16F1503 microcontroller from Microchip controls everything including the smart charging setup and LED indicators. TRRS jacks are used which is a breath of fresh air. Why? If using the Ni connected to a phone which seems to be what Periodic Audio is intending, you can plug in a set of headphones or earphones with an inline mic and media controller and not lose that functionality. I personally don't know of another amp that permits this. What else did they cram into this thing? How about a short depth microUSB connector that allows you to use any microUSB cable with it should you break or lose the included cable, or maybe you just want to use a longer one. Since this little device is going to be in close proximity to other electronics, they also added class IV ESD protection that can handle a 32kV surge. Unnecessary, and I love it. RF protection is in place too, enough to address 10 times the legal RF noise limit at 1cm.

The lithium polymer battery isn't huge at 280mAh but provides a good amount of play time with the Ni; 8-10 hours. More impressive is the charge time of between 20 to 30 minutes via USB. I see 20 to 30 because their product page says 30 yet the packaging says 20. Either way, it is not marketing fluff and it really does charge that quickly. From the USB 3.0 ports on my ASUS FX53V, the Ni charges to full in just under 30 minutes. For nearly 10 hours of play time, that's truly awesome and the convenience is unmatched among any other amp I've used.

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Using It:

There's not a lot to say about using the Nickel. Plug an aux cable into the input, plug your headphones into the output. It will automatically detect them and turn on as evident via the bright green LED located between the two ports. Just be sure to always plug the headphones in last else you experience a massive and unpleasant POP that leaves me worrying about the health of the headphones/earphones I just plugged in. As the batteries drain, the LED will change from green, to yellow, to red. When charging is needed, plug in the USB cable and wait 20-30 minutes. You don't have to stop using the device either since it works while charging.

In terms of sound quality I found the Ni impressively balanced and uncolored. It doesn't add in additional warmth or bass, jack up the midrange, or crank in extra treble. Using it with my HiFiMAN Megamini reduces the warmth of that DAP and as such I don't feel the need to always pair it with neutral to bright earphones. Pairing it with a flawed budget offering like the Ruizu X02 doesn't fix the early low end roll off of that device, but it does do an amazing job of correcting the harsh upper ranges. The Ni doesn't “fix” the source device, but it can mask some of their shortfalls.

With more demanding to drive gear and/or that which benefits from amping such as the Brainwavz Alara, HiFiMAN Sundara, ADVANCED Alpha, etc., the Ni makes for an outstanding partner. The volume boost is only 6dB, but it allows you get to the most out of your DAP or phone's standard output without having to worry about distortion should you push it. It results in good, clean power that allows you to listen at pretty much whatever volume you want. However, when pairing it with sensitive headphones like the Campfire Audio Solaris, Cascade, or TFZ Secret Garden HD, things aren't quite as peachy keen. The source, be it a DAP, phone, laptop, etc. makes or breaks the experience.

I noticed there is always some hiss with sensitive headphones, and depending on the source that hiss is going to increase or decrease. My HiFiMAN Megamini, F.Audio S1, and HiFi E.T. MA8 all pair poorly with the Ni, MA8 in particular, adding quite a bit of extra background noise into the mix. My LG G5 and G6 fare better, akin to levels present when having earphones and an aux cable plugged in so the device is on but no music is playing. Noisy but plenty tolerable and masked when music is playing. My Shanling M0 really cleans everything up and is the best pairing of all my devices with the cleanest background of the bunch by far. The M0, Ni, and Campfire Audio Solaris together is a trifecta of perfection providing one of the most satisfying portable listening experiences I've had to date. The Shanling M1 and my PSVITA also worked well with the Ni.

Final Thoughts:

I'm somewhat torn on the Nickel. On one hand I love the tiny size and excellent driving power it outputs. The design isn't particularly attractive, but it's small and durable and the device is about as easy to use as it gets. No dials, no knobs, nothing to go wrong or fiddle with. On the other hand, the basic looking shell and lack of features like gain, bass boost, volume control, etc. make the 299 USD price tag difficult to justify. Until of course you look at the component parts and the engineering that went into making the device. That brings the price somewhat back into line with expectations. But then you experience severe and painful popping if you plug the headphones in before the source. Always go source then headphones. With the Ni there seems to be a lot of give and take. Lots of “X is great, BUT, watch out for Y.”

The size is very appealing though. I don't like carrying around bulky, heavy, devices regardless of how competent they are, like the Auglamour GR-1. Amps that skew the sound signature, like the Walnut F1, reduce compatibility with various earphones and headphones since it risks boosting treble too much. None of this is an issue with the Ni though it is way more picky about earphone sensitivity, and especially the source device, when compared to any other amp I've used. When you start pairing the Ni with sensitive iems, you need to be very choosy about which source you use since there is a good chance the quantity of background hiss will be overwhelming. I'm lucky I have a number of DAPs and devices to mess around with since only a small handful of them retained a nice, clean background. The rest were noisy enough to require either an uncomfortable volume level to compensate, or were simply unlistenable, like the Solaris -> Ni -> MA8 combo. You can bring something like the iFi iEMatch into the mix to deal with the hiss but that negates the volume bump provided by the Ni. You also find yourself with a silly chain of devices that gets cumbersome to carry around, eating away at the size advantage and simplicity.

The Nickel clearly isn't for those that like to tinker and toy with their sound. It's an amp, and that's it. The few features it has are convenient like auto-on/off and especially the impressive charge time. That said, it seems like a device made for someone already deeply invested in the hobby, not newcomers. Someone who has lots of sources and headphones can mix and match to find which pairings work best with the Ni. It would also be good for someone that listens primarily to headphones with lower sensitivity and higher impedance since the hiss issue is completely nullified, leaving you with a tiny, powerful amp that makes pretty much anything mobile.

I like the Ni and will certainly continue using it beyond this review, but it is tough to recommend to its intended audience; mobile users. Its pickiness with source when using sensitive headphones and iems, which most are when it comes to devices intended for mobile use, might be a deal killer. That said, if you're interested in the Ni and plan to use it with headphones that require amping, go for it. You'll be treated to a compact, powerful device with a flat signature, decent battery life, and an amazingly short recharge time.

Thanks for reading!

- B9Scrambler
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Thanks, confirmed what I thought since doesn't have a dac and would be using from a pixel with terrible sq. Thank you for being honest and not cowtailing, saves people literally 100s of hard earned $$$.