Huge driving power, Highly compact design, Transparent sound, Low output impedance, Mic pass-through
Battery passively discharges, Slightly higher noise floor
The Ni represents a versatile upgrade, bolstering dedicated sources with huge power and lowering the output impedance of low-quality ones.
Periodic Audio is a US-based company founded by a handful of audio enthusiasts. They design and tool all of their products in-house with a focus on quality material choice and streamlined portable usability. Periodic is most renowned for their high-performance dynamic driver earphones, however, with the Ni, the company have turned their sites towards enhancing the wider audio experience. This is a portable amplifier with stunningly good output power and a highly pocketable design. It comes with a $299 USD asking price which seems substantial given the size of the device. However, make no mistake, they’ve made every mm and gram count with this one. See Periodic Audio’s website for more info and store links.
I would like to thank KS Distribution very much for their quick communication and for providing me with the Periodic Audio Ni for the purpose of review. All words are my own and there is no monetary incentive for a positive review. Despite receiving the amplifier free of cost, I will attempt to be as objective as possible in my evaluation.
Frequency Response: 8 Hz to 80 KHz
THD + N: < 0.005%, 20 Hz to 20 kHz
Power Output: 250mW Continuous @ 32ohms
Damping Factor: >100 @ 32 ohms
Run Time: 8 hours, typical
Charge Time: 30 minutes from full discharge
Dimensions: 50 x 30 x 18mm
Jack: 3.5mm TRRS (mic pass through)
The Pitch –
High output power
The Ni is easily one of the smallest portable amps I’ve tested, on par with something like the Fiio A1. Despite this, the amp outputs as much power as a high-end DAP, 250mW continuous into a 32ohm load and almost 500mW into a 16ohm load, in fact. That’s a staggering amount of power, for reference, the A1 outputs 78mW into a 16ohm load. Furthermore, the amp has a 6.5dB gain so it will effectively double the maximum volume of the source.
Split power supply
Though compact and high in power, the amp provides a very liveable 8hrs of battery life. As it uses a discrete +/-5v power supply for the audio circuit, it can be charged during use without affecting sound quality. This should also translate to lower noise and high fidelity; power is a hugely influential factor on sound quality yet it is often overlooked as the quality of implementation is difficult to quantify.
Periodic’s website states how the Ni “Breaks the laws of physics” and surely that appears to be true when handling the device – it is absurdly small. With a polycarbonate construction, the amp is also incredibly light and not at all cumbersome to use day to day. The design language is clean and minimal with arrows denoting the input and output alongside debossed periodic logo. The polycarbonate exterior has a matte finish that resists oils and smudges while providing additional tactility. The edges on the rear are slightly sharp and there are clear seams, however, subjectively these imperfections suit a hyper-powerful micro amp developed in-house by a team of crazy audiophiles.
I think there are clear applications for the Ni given its dimensions. Of course, it complements a smartphone, but more so, I found the amp to pair perfectly with BT receiver such as the Fiio BTR3. With a Velcro strap to stack or simply some reusable 3M double-sided tape, this makes for a perfect pocket rig. Of course, the plastic construction doesn’t feel quite as sturdy as the metal and glass BT receiver, but for the uninformed, polycarbonate is no ordinary plastic. I’ve been carrying the Ni with the BTR3 in my pocket alongside my house keys for months. And where the BTR3 has developed marring on its frame, the Ni is unscathed. I believe this bodes well for the robustness of this product despite its lightweight feel.
The amp has been designed for simplicity and, in turn, is plug and play in operation. There is no power switch, instead automatically powering on when both input and output are connected and powering off when either is removed. Between the two 3.5mm jacks is a status LED that glows red, yellow and green to denote remaining power. The amp charges via a micro-USB port on the opposing side. It should also be noted that the jack is of the 4-pin variety so it can pass through remote commands and mic which is a nice touch. You will require a 4-pin interconnect cable to the source and the source itself will have to support TRRS too, for instance, most BT receivers don’t.
I didn’t find the use of a 4-pin connector to cause an unreliable connection as some other sources do. The amp also has no volume control, it simply scales with the source, aligning with Periodic’s focus on ease of use. I found it to offer a versatile range, getting just quiet enough for my most sensitive monitors and ear-splittingly loud when turning up the source. Battery life is rated at 8hrs on high volume which I was able to beat consistently. That said, the amp does passively discharge over time meaning it’s important to keep it topped up and in daily rotation.
For the Ni, I would like to first assess whether it nails the essentials; a linear frequency response, low-output impedance and black noise floor. In the following sections, we’ll determine how good this amplifier is objectively followed by subjective listening and comparisons/pair-ups to determine price/performance and optimal use cases.
Frequency Response –
Testing Methodology: RMAA via Startech External Sound Card
The Ni has a perfectly linear frequency response besides rolling-off progressively below 50Hz by ~1dB. The graph makes this seem worse than it is as, in reality, such a small deviation is not audible, the Ni has quite a full-bodied sub-bass presentation. Due to the quality of my sound card, I am unable to reliably test other measures such as distortion and crosstalk so they will be used as a personal reference only. Qualities here can impact the sound in subjective listening.
Output Impedance & Hiss –
Testing Methodology: SPL volume matched comparison through an inline splitter to JDS Labs Atom + Khadas tone board to Campfire Audio Andromeda
The Campfire Andromeda is extremely source sensitive, quickly losing bass quantity with even a slightly elevated output impedance. With that said, I can safely conclude that the Ni provides a very low output impedance below 1.5 ohms as I was unable to detect a difference in sound signature between the Ni and Atom nor when connecting an iFi IEMatch to better modulate volume. This speaks very well for the Ni’s versatility. Hiss is another story, however. It was more prominent than my other portable sources albeit, those coming from older portable amps will still likely experience a cleaner sound here. It was audible when music was playing at low listening volumes on the Andromeda alongside other sensitive high-end IEMs like the Fibae 7 and Noble Katana.
In fairness, the hiss isn’t too obtrusive, being fairly low-frequency and those that listen at medium to high volumes likely won’t have this issue. The noise doesn’t increase when the device is charging nor have I experienced any EMI or other interference from the source. Still, low volume listeners with sensitive BA earphones that are sensitive to hiss will want to look elsewhere as it is noticeable. The Ni is, therefore, suitable for every driver configuration but ideal only for medium to low-efficiency earphones.
Testing Methodology: SPL volume matched AB with in-line splitter between Pixel 4 + Cozoy Takt-C + Ni and JDS Atom + Khadas tone board to Custom Art Fibae 7 (flat impedance), Final sweep with Tone board + Ni vs Tone board + Atom
The Ni provides a well-extended low-end lacking the last iota of sub-bass drive provided by my desktop setup but providing very convincing weight, nonetheless. To compensate, the Ni possesses a slightly fuller bass note body with a touch of emphasis in the sub-bass granting it a full and powerful foundation. The desktop setup provides a very concise note attack and slightly longer lingering decay while the Ni has less aggressive attack, lacking the same note solidity, paired with quicker decay that provides similarly convincing pace and coherence. Bass is linear through the mid and upper-bass with a neutral tone and control is high resulting in a reasonably clean presentation with good mid-bass definition and separation if not the most defined rumble and physical slam at the very bottom.
The midrange also demonstrates good transparency to the source. There’s a slightly thinner note body which could be a result of a less substantial sub-bass, and less note resolution, in turn. Conversely, a hint of warmth in the midrange grants it pleasing euphony while its note structure permits higher separation and, in a sense, clarity; being well-balanced overall. The presentation remains appropriately dense and smooth through the upper-midrange so these deviations aren’t hugely apparent unless under close scrutiny. For all intents and purposes, the midrange timbre is accurate and natural.
Highs continue this theme, delivering a touch of additional crispness within the foreground at the expense of instrument body. There remains great control with excellent detail retrieval and definition. Decay is slightly truncated and, as such, instruments don’t possess a perfectly accurate timbre and texture. The background is not quite as clean as the Atom with slightly grainier transients if not necessarily any brightness, it simply lacks the same resolution here. Still, it delivers strong background detail retrieval and a strikingly similar sense of distance to the Atom. This is a well-controlled presentation on a whole and an immediate step up from most vanilla portable sources.
The soundstage is also quite pleasing, it is large if not especially three dimensional, with a focus on width especially. Separation is excellent and imaging provides good directionality with sharp directional cues if not perfect coherence with regards to panning and note structure where the desktop setup is perceptibly more agile and involving. Again, expectations must be tempered for a portable source.
Driving Power & Comparisons –
Fiio BTR3 + Hidition NT-8 (110dB, 16.5ohm): Introducing the Ni into this setup, I hear slightly more sub-bass power and extension alongside greater dynamics. The tone is more transparent, the BTR3 being warmer, the Ni grants a cleaner mid-bass tone due to noticeably higher control. Most notable is more concise attack and quicker decay resulting in higher definition overall. Mids are similar in presentation, slightly fuller on the Ni with higher note resolution but with more clarity on the BTR3. The Ni provides cleaner treble transients with greater detail retrieval. The Ni has a slightly larger stage with better separation, similar imaging performance. Minimal hiss on either.
Shanling M0 + Final E5000 (93dB, 14ohm): Volume 24 on high gain, 17 with Ni. The E5000 loves power and saw good results with the Ni. Immediately, there was more sub-bass extension, power and slam, greater dynamic range in general. The tone remained unchanged despite enlarged note size. Higher driver control with greater definition and bass separation was also observed. The midrange presentation was similar with just slightly more note resolution, clean and well-layered overall. The Ni provided sharper high-end transients with higher detail retrieval. Similar soundstage dimensions but with more coherent imaging with stronger centre image and greater separation due to cleaner transients. No hiss on either.
Pixel 4 + Takt-C + Hifiman Sundara (94dB, 37ohm): The Takt-C required 55% volume and 40% with the Ni attached – also be aware that volume control is not linear on Android devices so you will get a lot more volume at higher settings. The most immediate difference was an increase in dynamic range. I didn’t have to turn up the volume to hear treble details and achieve visceral bass slam, the Ni provided deeper extension with more solid slam alongside greater driver control yielding higher mid-bass definition and separation at a comfortable volume. The Ni provided a slightly sharper transient response and a cleaner sound throughout. Highs were also more detailed and extended with a larger soundstage and more apparent layering. No hiss on either.
JDS Atom + Hifiman Sundara (94dB, 37ohm): As compared to my JDS Atom, it was a shockingly similar experience in terms of dynamics and extension. The Atom was a touch cleaner in the highs with a more expansive soundstage. The Atom also provided higher resolution throughout. There was a touch more heft in the sub-bass, however, the difference was not nearly to the same extent as that between the Ni and my portable sources alone than stepping up from the Ni to the Atom. This obviously won’t replace your desktop setup or your high-end dedicated sources, they are clearly more resolving, but it will get close in terms of dynamics and drive at a reasonable price and with a stunningly portable form factor. No hiss on either too.
Suggested Pair Ups
With a 250mW output power into a 32ohm load, the Ni has heaps of power and experiences no difficulty driving basically any IEM or portable headphone and will do well with some full-size headphones too. Even with more efficient gear, an appreciable difference to dynamics and driver control can be heard. There’s also plenty of volume on tap for low-sensitivity and high impedance designs such as those implementing Sonion EST drivers. The Ni pairs brilliantly with smartphones, BT receivers and small DAPs such as the Shanling M0.
The Ni is actually quite a unique product in this day and age. Though I fondly remember daisy-chaining portable amplifiers to my smartphone, products such as those from RSA and Headamp haven’t been updated for some years as the portable stack has fallen out of fashion in favour of all in one solutions. The Ni modernises these archaic designs, providing a much more polished experience overall. It measures well and has a very low output impedance so it won’t skew the signature of low-impedance multi-driver earphones that have also become increasingly complex in recent years. The Ni, therefore, represents the resurgence of the portable stack and a return to the golden age of HiFi where power and dynamics reigned supreme. This does come with one caveat, the noise floor, which is higher than most sources but not unbearable. If you’re looking to transform your portable listening and don’t mind a bit of hiss on sensitive monitors, the Ni is a tremendously convincing package.
The Ni is available from on Periodic Audio and Hifiheadphones (International) for $299 USD at the time of writing. I am not affiliated with Periodic Audio or Hifiheadphones and receive no earnings from purchases through this link.