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Periodic Audio : Carbon IEMs and Nickel Headphone Amp

The Carbon model is the best IEM from Periodic Audio, an American headphone manufacturer, and their Nickel Headphone Amp is used to pimp performance of headphones – I get to grips with both in this review.

According to Periodic Audio, with Carbon there are no electrical components between the amplifier and transducer with this design, meaning a direct signal path of the audio to preserve the minutiae of musical detail. Also they say the strong anti vibrating polycarbonate enclosure allows you to hear these details, translating to wider spaciousness.

This is uncanny as when I started listening, without looking at the manufacturers comments, I wrote down in my notes that they present spaciousness. These single driver IEMs have a nice open presentation with a big spatial soundstage which creates good insight into music and coming with a certain delicacy. Sound-wise, a little like being in a big cave with less dispersive IEMs on.

A look at both products in my film here

The product is basic looking and appears cheaper than it is because the cables are quite thin and the driver enclosures are simple non-elaborate plastic affairs. I like the way Periodic Audio use the nomenclature of chemical elements in the periodic table with the atomic number and symbol written on the box. Imagine….., yes!!, they could call the next product Kr for Krypton, or maybe even Kryptonite if brave. Chord Electronics, look out, they could have you on quirky naming!

Periodic Audio Carbon and Nickel Review
Periodic Audio Carbon and Nickel Review

They have a slightly thinner, less full bodied sound to some MAS Audio Science X5i headphones I’m testing at the moment, but at the opportunity cost of a different type of spatial sound. If you like soundstage in IEM headphones then the Carbon is one to try.

But they are quite balanced too, the treble is just right and they are fast and dynamic. Great for electronic music. Trying the seminal track I use to test treble – Attached from Orbital’s Snivilisation album, treble is perfectly on cue.

Using them with an iPhone without any external DAC or headphone amp, they can be much less resolving than when used opposingly. Not surprising, but anyone testing headphones should be aware.

Periodic Audio Carbon and Nickel Review
Periodic Audio Carbon and Nickel Review

I found using them with a coffee table system of a Chord Qutest Digital to Analogue Converter (DAC), JDS Labs headphone amp and a Yamaha WXC-50 streamer, got the best out of them. If maybe quite an incisive sound. Overkill too perhaps, but a good test nonetheless.

Some will prefer a slightly warmer richer tone and using DAC filtering or appropriate balance settings on your portable music device, to achieve so. The Qutest DAC has such filters and keeping it on the warm (red) filter gives the Carbon headphones a noticeably different balance.

Using an Audioquest DragonFly Cobalt , the sound gets a boost in the tonal stakes which makes these headphones very nice indeed. Bags of detail and soundstage, but with the warmth and natural detail of the DragonFly in the mix.

Periodic Audio Carbon and Nickel Review
Audioquest DragonFly Cobalt with Periodic Audio Carbon IEMs

The same story above is true with different audio players, including a FiiO X1II and an iPod Classic, so I won’t repeat myself. 

So if you are into a tonally rich, full bodied sound, and intend to use them alone then these might not be for you. But there is more than one way to shine a penny. And as these are worthy headphones and of very good quality that improve as you throw better electronics at them, they are no slouches in any sense at all. Of recent, I found their balance more natural compared to some similarly priced IEMs in Final B3’s and Campfire Audio IO’s. These IEMs presented detail and treble in too forward a fashion, making prolonged listening more challenging.

Periodic Audio Carbon and Nickel Review
Periodic Audio Carbon and Nickel Review

To any headphone novices, these IEMs are a step up from sub £100/$100 types. It’s hard to stomach paying for quality headphones when they are naturally so small. However accounting development costs, and that sound quality is extended above the types most people pay for,  these headphones are worthy. Especially if you want the characteristics I’ve highlighted.

Give me a Nickel

I found using these headphones with the Nickel amp, bass is clearly deeper, faster, and more impactful and accentuated. Also as they are coping better, detail is up, but they don’t allow proceedings to stray from their trademark open expansive sound. In fact if anything, the Nickel amp accentuates this characteristic. They are clearly more dynamic than without the amp. As expected, you can turn volume down to get detail, which is great in not having to blow your eustachian tubes up.

The Nickel headphone Amp is one of those products that looks nothing much, it’s a simple box about the same size and shape as a Duracell 9volt battery. Also being from hardened plastic. I like its pleasing green coloured operating LED when two 3.5mm sockets are hooked up. Apparently utilising Periodic Audio’s own uniquely engineered smart switch technology – where the unit turns on when the 3.5mm connectors are inserted. It uses a fixed gain output with no volume control, so you change volume on your device.

Nickel Headphone Amp (centre) with iPhone SE, AQ DF Cobalt and Carbon IEMs

Periodic audio say that sound is improved too by using a dual voltage converter which generates dedicated power independent of USB switching noise. This means sound quality is not compromised. It’s been long known that noise pertaining to USB power rails can affect the sonic qualities of audio. The Nickel does what it says on the tin and especially when you hear it.

There is more to sound than just plastic, thank goodness, as otherwise we’d have to throw away most of our HiFi or audio gear. Put it this way, once you take it out of the chain, you’d never accept the sound as it once was direct to your player. In this sense it substantiates its worth as an added option and a bit like power conditioning in HiFi. We talk about what the fuss is over using a conditioner until after trying it for a few months, like I have, you’d rather not have to give it back! Much like the Isol-8 SubStation Integra.

The Nickel is stated as supplying 150mW into 50 Ohms, 250mW into 32 Ohms, or 270mW into 16 Ohms. By how much this is improved from an iPhone I’ve no idea as Apple don’t appear to publicise power output figures.  However whether the improvement of the Nickel is one that is improved upon over your phone or portable music player, you’d need to try it to hear its worth. Its isolating abilities I’ve mentioned do have an effect too. Obviously not just the effect of improved amplification, but much will depend on how your devices DAC performs and how it works in synergy with this headphone amp. One thing is for sure, allowing the Carbon headphones to work more optimally with improved power gives them space to breath and perform better. Added detail and dynamics are the key areas, as always, and warmth is bolstered to acceptable levels now.

It doesn’t quite give the same insight into the depths of music with an iPhone SE as the similarly priced Audioquest DragonFly Cobalt does.

Using just the Nickel and Carbon IEMs is a strong combination

You can charge it in use with no effects on sonic quality and this process is quick using the micro USB, with its LiPo (lithium polymer) battery. It lasts for 8 hours according to the spec, which is about what I got. Also, it doesn’t have any effect on the battery life of your phone, unlike using the DragonFly Cobalt which is a honey monster in munching batteries.

With an iPhone, using the Nickel with over ear Grado SR225 headphones , bass is deeper and detail is slightly more refined, but sound is definitely less flat and more dynamic. A useful improvement. They clearly aren’t anywhere near as well driven as using the JDS Labs Atom amp which is outputting around 4 times the power, but for portable use it is definitely a worthy improvement. With a FiiO X1II, the improvement is even more dramatic so bear in mind that what you get out will depend on the source. The same story as before too; the sound is flatter and less dynamic without the Nickel.

Periodic Audio Carbon and Nickel Review
Periodic Audio Carbon and Nickel Review

Using the DragonFly Cobalt and Nickel with the Carbon IEMs is unsurprisingly very nice indeed. It really brings out the best of these headphones, with a perfect combination of balanced tone, soundstage and better refined detail. Again warmth is very good. It might be a faff plugging everything in or carrying around, particularly with the Apple USB adapter that has to be used, but this combination significantly improves these headphones.  

Using the Nickel with some Focal Clear Over ears into an iPhone shows what the Nickel is capable of again. Whilst clearly not a set-up that will get the most out these Focal’s, a good test nonetheless.

Remember that it’s not just a question of comparing the headphones impedance (how hard they are to drive) and sensitivity (how loud at any given power input) to determine how well the headphones are likely to sound for any given power input. It’s too about getting them performing well by having power within the realms of dynamic / detail capability. This is the worth of the Nickel headphone amp, and as with the Carbon IEMs, they come recommended.

JDS Labs Atom Amp with AudioQuest DragonFly Cobalt
Using an iPhone or iPad into the DragonFly Cobalt as pre amp & DAC and using the JDS Labs Atom headphone amp worked very well.


Carbon Headphones
Frequency Response ; 12hz to 38khz
Impedance : 32 ohms
Sensitivity : 98 dB SPL at 1mW in ear
Power handling : 200 mW continuous
Peak SPL : 121 dB
THD : less than 0.2% THD at 1mW

Nickel headphone amp
Frequency response : 8hz to 80khz
THD + N : < 0.005%, 20 Hz to 20 kHz
Power Output : 250 mW Continuous, 32 Ohms
Run time : 8 hours typical
Charge time : 30 minutes
Size : 50mm X 30mm X 18mm (L,W,H)
Weight : 20 grams

With DACs quite good in phones but amplification not so, watch to find out why the Nickel makes sense!


Carbon IEMs – $400/£400
Nickel headphone amp – $300/£300

Manufacturer Details

Periodic Audio
4882 McGrath Street Suite 100 Ventura, CA 93003
Tel : +1 885 724 4367
Website :
Email :
Distributed in the UK by HiFi Headphones (Shoreham by Sea) @

Written by Simon Price

I'm music lover who shares experiences of faithfully reproduced audio in an ENGAGING way with HIGH VIDEO PRODUCTION VALUES. I enjoy and make reviews as I love audio gadgets, being a voice on audio and producing creative videos that ultimately benefit the industry and new participation. I keep technicalities easy, as I believe great audio serves music and music is inclusive and to be enjoyed by all!

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