Honey, I Shrunk the Headphone Amp
Size, great power output, long lasting, easy to use
nothing included to help attach this to your source
Thanks to Dan at Periodic Audio for arranging a sample of the Nickel for the purposes of this review. The thoughts here are my own subjective opinions based on time spent listening to the Nickel. They do not represent Periodic Audio or any other entity. I have no affiliation with Periodic Audio and am in no way connected with the company.
I have been an avid listener of music for a very long time. Throughout my years of acquiring stuff, I feel that I have gained an understanding of the synergy between the music and the hardware that presents it to us. I love gear and, more importantly, the music.
This review will not be encumbered with specs and charts. I wanted to disclose what I heard and how I used it by the seat-of-my-pants (which is how I think many of us get to know what we like and dislike).
The Periodic Audio Nickel amplifier is a small portable headphone amp. It is about the size of a 9V battery but weighs a fraction of it. Three ports ( 3.5mm input/output and a micro USB B charging port) and an indicator light that shows power status and battery charge capacity adorn front and back. There are no volume or power on controls (more on that later). It is super-lightweight and made from a polycarbonate material.
The name harkens to the rest of their product line, items named after periodic elements: Beryllium, Titanium, Magnesium and now Nickel.
What’s in the Box
Periodic Audio takes a minimalist stance on their packaging. A very simple box with specifications, charts and description opens to reveal the prize. It is very similar to the other products I have seen from them. It comes with the amp, simple instructions, a medium 3.5mm to 3.5mm interconnect cable and a short micro USB to USB-A charging cable.
I like the low-key approach. Most of the time the packaging is tossed so why spend big money on it? I’d rather spend the money on product, not marketing.
I am using a variety of digital players (Fiio X5iii and X3ii, Cayin N5ii, Hiby R3) as well as my IPhone 7 as the sources. The headphones used were: Sennheiser HD-6XX, AudioQuest Carbon NightOwl, HifiMan HE-400i, Campfire Audio Lyra, Cypher Labs C6IEM, Fiio FH5 andFA1, TFZ Queen and Ibasso IT01 and IT03.
This thing is small. I mean tiny. I wasn’t expecting it to be this small. I thought to myself, well probably doesn’t have much grunt to it. Boy was that a mistake. The website boasts it delivers 150 mW into 50 Ohms, 250 mW into 32 Ohms, and 270 mW into 16 Ohms. That seems conservative to me .
It has a quick charging time (about 30 minutes) and battery has real-world usage time of about 10 hours or so. The light turns green when all connections are made to show the unit it powered on. Yellow tells you’re getting close to shutdown (maybe like 15 minutes) and red is imminent power off. When charging it reverses the step red-yellow-green, flashing to tell you’re in charging mode. Solid green is full.
The one really neat feature was the auto-sensing function. There are no power-on buttons. Simply plug the amp into your source and plug the headphones into the Nickel and it turns on. Unplug either and it turns off. Simple. I can’t remember all the times I used other portable amps and when finished, I forget to turn it off, only to discover when needing it later that it was totally dead. This is one smart little amp.
The analog, yes analog, ports are snug fitting. You really need to make sure your plug clicks into place. Takes some getting used to but it will ensure that nothing falls out by accident in your pocket.
The input is analog meaning you feed this from your headphone out on your device. You can retain the DAP’s or phone’s volume control. I was told this due to their unique set-up:
No worries with double-amping; the amp in your player is feeding Nickel's 10 kOhm input impedance, so it's doing NO current or power - just more voltage gain. So basically there's no "double amping", your player's amp is now a preamplifier (since it's supplying essentially zero current/power) and that feeds into Nickel.
We did this because we think that the dominant use case will be with cellphones, so we optimized the built-in gain for cellphone use (which typically is 1 to 2 Vrms). And in that case, more gain means you can use less of the volume adjust range in your cellphone (instead of a usable 12-16 clicks, if we had more gain, you may only have 6-8 volume steps between "really quiet" and "too loud").
The only thing really missing was a way to strap this to a source. Over time, I have had many portable amps and have accumulated various silicone bands and such. Luckily, I had one that was relatively non-intrusive. I know that they can’t possible imagine all the possible combinations that would ensue, but maybe offering some kind of ‘universal’ band to aid in pairing the Nickel to a DAP or phone would be helpful to those who are jumping into the portable scene for the first time.
So finally, I bring it all around to sound. What does this thing do in terms of volume?
First off, it is quiet. Even with sensitive IEMs Like the Lyra, it is dead quiet.
There is some really great power output here. I was a little afraid that this may color the sound coming from my source. I couldn’t detect any coloration. Some amplifier’s output can seem sterile or sound harsh. Not the Nickel. It was invisible to my listening - just nice clean power.
When using with my DAPs, I found that I needed to drop the volume by maybe 20-25 steps for comfortable listening. For example, when using the Hiby R3, without the amp, I would listen at maybe volume level 40-50, with the Nickel, I would bring it down to about 20-30.
The bass is really punchy. Nice and tight and extends pretty low. Mid-range had natural, decent details revealed and instrument separation seemed accurate. Soundstage wasn’t as wide or tall as I expected but not closed in either. Treble is nice, some sparkle but not shrill. There’s a nice roll-off.
All the IEMs I used sounded great. Not any glaring irregularities. No hiss encountered. The unit did seem to meet some trouble when faced with the HD-6XX and HE-400i. These can be challenging to any player/amp due to the resistance or driver configuration. The Nickel held up but I found that I needed to get to almost max volume setting to get it decently comfortable. There was never any clipping - just pushing the little guy to its limits. Kudos to the PA team for delivering such a little device that can go that far.
Since the Nickel is a portable amp, how many people would wear full sized HPs around outside? Paired with IEMs seem to be the sweet spot. I don’t subscribe to any streaming services so I cannot relate my experience there. All my files are local and I tested a variety of types. Everything from low bitrate MP3s to quality FLAC and DSD.
What was clear was that due to the transparency of the Nickel, bad files sounded bad but good files sounded sweet. I found myself skipping over the MP3s and really focusing in on the FLAC/ALAC ones I have. Miles Davis' Kind of Blue was superb. All the nuances of his horn and breath were revealed. Chris Isaak Blue Spanish Sky was exquisite. The timbre of Isaak’s vocals was riveting. The club scene on Bill Evans Trio's Time Remembered was encompassing. I could pick up the sounds of glasses tinkling from behind and voices of the audience at tables both distinctly left and right while the trio was dead center.
I have to give some serious applause for Periodic Audio to bring to market such a tiny, powerful little amp. The Nickel is truly a wonder. Brought power where it was needed without masking or changing the sound from my players. It drove all my headphones with aplomb and never cried out for mercy. It is almost unthinkingly easy to use. With the ability to drive almost everything and adding to an underpowered source, like my iPhone, and still being able to fit this into my pocket with nary a concern, is testimony to the engineers and product planners at Periodic Audio. I was thrilled to own their Be and Mg IEMs and marveled at their simplicity yet was astounded by the sheer musicality they presented. Now we see what that evolved to in the Nickel.
Small. Simple. Powerful.