It's a Headphones Thing

A Headphones Reviews Blog

[REVIEW] FireStone Audio Fireye Mini & Fireye HD Portable Headphone Amplifiers


Firestone Audio (“FSA”) is a Taiwan-based audio-products manufacturer, established in 2003. They’re mostly known for their DACs, Amplifiers & Headphone Amplifiers. Not too long ago, the company had replaced the products from the “Fireye” series (their portable line of products) with a few new products, two of them, the Fireye HD and the Fireye Mini being the subjects of this review. The HD is the top of the line, priced at $350-$400, while the Mini is the cheapest product from that line, being priced at only around $40.

Technical Specifications:

Fireye HD:

  • Power Structure: Built-In Rechargeable Li-ion battery
  • Battery Life: More than 8 hours when fully charged
  • Charging Time: 5 Hours via USB, 2.5 Hours via DC
  • Headphone Impedance: 16 Ohms – 600 Ohms
  • Main OPAmp: TPA6120
  • THD: 0.0005%
  • Weight: 155gr

Fireye Mini:

  • Power Structure: Built-In Rechargeable battery
  • Battery Life: Around 12 hours when fully charged
  • Charging Time: 3 Hours
  • Headphone Impedance: 32 Ohms – 600 Ohms
  • Main OPAmp: TI-DRV601
  • THD: 0.00068%
  • Weight: 14gr
  • Dimensions: 40X24X9mm (DxWxH)
the HD's packaging

the HD’s packaging

Packaging– both amplifiers are packaged in cardboard packagings. The Mini’s one is a more “retail-looking” one, while the HD’s one is a plain white packing with a label on it which says “Made In Taiwan”, a paper sleeve with the model’s name, and FSA’s logo, all on its front.

the Mini's packaging

the Mini’s packaging

The mini’s packaging has an illustration of a hand-palm around (it’s a nice way to show how small the Fireye Mini is) a plastic “window” in its front, which you can see the product through it.

Accessories- The Mini comes only with a USB charging cable and with a short interconnects cable, but I guess that it is ok when looking at its low-price. On the other hand, the HD comes with the same two cables plus a wall-charger; with a product that costs $350-$400, I would’ve expected to get at least also a rubber-band to lock my DAP to the amplifier, and a carrying case would’ve been nice to get either. It isn’t that “critical”, but it would’ve left a better taste if there was a nicer accessories-pack. I found the interconnects cable that was provided with both the Mini and the HD to be of not a really good quality, and the one that came with my Mini didn’t even work.

Building Quality & Design: The HD and the Mini are rather different design-wise; the Mini is offered in many colors, and is a quite “young-looking” amp, while the HD is offered only in a single color-scheme (silver-black-gray) and it possesses a more “professional”, “classy” and “mature” look.

The HD is fully made of aluminum (the part where its name is written on is honed by sand, and has a different texture because of that), apart from its front and rear “panels”; they are made of black plastic.

the HD's front panel

the HD’s front panel

The front panel has the bass boost and gain switches, the volume control knob and the input and output sockets, that are both recessed, a thing which makes it annoying to put the plugs into them all the way through.

the HD's rear panel

the HD’s rear panel

On its back we can find the DC input, power switch and the USB charging socket. Being mostly made of metal makes it very tough, strong and durable. On the other hand, it is a bit scratch-prone – my unit already has a few scratches on its top surface.

the HD is simillar in size to my 4th Gen. iPod Touch (Seen here)

the HD is simillar in size to my 4th Gen. iPod Touch (Seen here)

It has a nice form-factor – about the size of my 4th Generation iPod Touch, which I’d consider quite portable. It’s quite slim too, and I didn’t find it a problem putting it inside a pocket together with my iPod. Its weight is around 150 grams, not too much, and something that is still portable enough and not too bothersome to carry around.

the Mini's front

the Mini’s front

The Mini has a lot more simple and minimalistic design; its PCB-board is covered by a rather weird and tacky rubber-made chasis/housing, which doesn’t seem to be shock-proof or protect the amplifiers inner-components.

the Mini's back

the Mini’s back

Also, dust tends to stick to it when it’s being left outside of the drawer, which is quite annoying. It has a small piece of rubber on its top which you can use to hang the amp to your DAP, for example. It is the tiniest amplifier that I’ve ever seen or heard of; its size is about a half of the size of the FiiO E6! Like some other small amplifiers, also the Fireye Mini doesn’t have a power button – it’ll turn on whenever you’ll connect something into its headphones socket, and a blue LED would start to light when it’s turned on.


Additional Functions: The Fireye Mini has no additional functions at all (it doesn’t even have a volume control), so we’ll just move on to talking about the HD. It has a two-level gain switch, which is 1.5x on the low gain mode and 5x on the high gain mode. It also has a bass-boost switch, which adds around 3dB when switched on. The HD “never” really turns off, as there’s something in its circuit design which causes it to stay open until the battery is completely empty (it doesn’t have a lot of volume in this mode though).

when the HD is turned on, we have a blue light from the LED in its back

when the HD is turned on, we have a blue light from the LED in its back

When the HD is charged, we have a red light coming from the LED in its back, while when it is turned-on we have a blue light out of it. I also liked the “low battery indicator” – when the battery comes close to being empty, the LED starts to flash, which is a nice feature.

Battery Performance: FSA promises around 8 hours of usage with a fully charged Fireye HD, and around 12 hours of usage with a fully charged Fireye Mini. I got around 5-4 hours with a fully charged HD and around 10 hours with a full charged Mini. I understand that the battery life depends on the volume too, but I haven’t listened to both amps in high volumes, so that was surprising to me, especially the bad results of the HD’s battery. My unit’s battery might be defective, but I cannot actually be sure about that. As for charging times, they’re a bit less than what is noted in the specs – for the HD it’s around 2 hours for a full charge from via the DC charger, and around 4.5 hours via the USB charger, while for the mini it’s around 2.5 hours.

Hiss: The Fireye HD is a quite clean amplifier; it had no hiss with most of the headphones and IEMs that I’ve tested with it, even not with the very sensitive and low-impedance LEAR LCM-5 CIEMs, but it surprisingly had some hiss and an annoying background noise with my ACS T1 CIEMs, which are less sensitive than the LCM-5s and have about the same impedance as them LCM-5s, as far as I can gather from specifications around the net. The Fireye Mini is a lot hissier than the HD, but that isn’t a fair comparison, as the Mini costs about 10th of the HD’s price. It does have some hiss issues with the likes of the T1 and the LCM-5 (and some other highly sensitive IEMs), but its hiss level is smaller than the one of the GoVibe MiniBox 2012 Version and of the FiiO E6 (when connected straight to the 3.5mm socket of my iPod, when it’s connected via an LOD it has some smaller levels of hiss).

the Mini (in the middle) next to the E6 and the GoVibe Mini-Box

the Mini (in the middle) next to the E6 and the GoVibe Mini-Box

Both the HD and the Mini don’t seem to suffer from electromagnetic interference when there’s a cell-phone nearby, which means that they both would be good for users that a cell-phone is their listening-device.

Sound: The Fireye Mini is a cute little amp, but nothing too audiophile should be expected from it; it does make the soundstage larger and more airy, adds a bit of clarity to the sound and makes the bass a bit more impactful, but that is about it. I’ve compared to two mini-amplifiers that I have in my possession: the GoVibe Mini-Box 2012 Version and the famous FiiO E6. The Mini-Box is absolutely better than it in every term sound-wise, most noticeably in the clarity. On the other hand, I’ve found the Fireye Mini to be better than the FiiO E6 in regards to the sound-stage size and imaging. It is a shame that the Mini doesn’t have a volume control and some EQ presets like the FiiO E6 has; having those could’ve made it “a fuller-package”. Because of the lack of a volume control, the Fireye Mini is completely unusable via a LOD. The Mini has a quite impressive driving power for its price – it managed to provide a nice listening volume for the 200 Ohms TDK ST-800, but the sound quality was not as good as with lower-impedance IEMs and headphones.

The HD has a neutral and transparent sound-signature, with a slight hint of warmness. I’ve noticed some significant additions in the clarity and cleanness, and also a tighter and more impactful and better textured bass. In addition, the detailing seemed to be slightly improved while using the Fireye HD in comparison to connecting the tested headphones straight to my iPod. It has a great driving power, managing to get the 300 Ohms Etymotic Ety Kids5 and the 200 Ohms TDK ST800 to very high volumes, a quite impressive thing. The bass boost option is nice: it adds a tight and good-quality bass in an amount that would satisfy most of the non-basshead users. The HD’s output has an impedance of about 10 ohms, which makes it not so ideal to use with some low impedance headphones & IEMs; such a high output impedance output makes some noticeable changes in their sound. It seems that it might have been designed for some bigger headphones rather than IEMs and low impedance stuff. I’ve also noticed some volume imbalance issues in very low volume, but that’s quite minor I guess.


Final Conclusion

The Fireye Mini & Fireye HD are both decent products that could’ve been a lot nicer if some of the problems in them that I’ve mentioned in the review would’ve been fixed. For the Mini, the main problems are the weird and un-protective housing and the lack of a volume control, while for the HD they’re the very short battery life, the high output impedance and the annoying recessed input and output sockets. I liked the HD’s elegant and classy design, tough building quality and the great transparency that it brings to the sound, while I was impressed by the Mini’s size – the smallest amplifier that I’ve ever seen.


Where to Buy? The MSRP of Firestone’s Audio Fireye Mini is $40 in the U.S. and 35 Euros in Europe. It can be purchased from FSA’s authorized dealers: U.S, Europe.

The Fireye HD has an MSRP of $400 in the U.S., and 199 Euros in Europe. It can be purchased from FSA’s authorized dealers: U.S, Europe.

I’d like to thank FireStone Audio for the review samples.


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