FiiO A5 Portable Headphone Amplifier

General Information

The FiiO A5 is the next generation portable amplifier and is the next evolution of FiiO's well-received E12 and E12A portable amplifiers.

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Pros: well built, quiet (noise floor) fairly transparent, good battery life
Cons: Poorly designed and implemented bass boost, gain is too high for some IEMs
My first Fiio amp was an E17 with its desktop E09 cohort. Today their amps have taken a backseat to first DAPs and now earphones. I recently mentioned looking at a new amp and Ngoshawk was kind enough to send his A5 for me to audition before purchase. I also have a walnut F1, a topping Nx5, and an Ibasso PB3 on the way to compare. I have owned an E11 and an E12 in the past but skipped the e12a as I didn’t feel the need to upgrade at the time. Now that my usage pattern has shifted to mostly IEM listening, I am in the market for an amp appropriate to that. I debated getting an E12a as they are still available, but the A5 was supposed to be the best features of the E12 and the E12a so wanted to give it a shot. The thought of combining the power level of the E12 with the noise floor of the E12a is a great idea. The question is, did they pull it off?


The A5 has an all steel chassis and feels very solid in the hand. I can’t find any size difference between the A5 and the older E12 visually and it is a perfect mate to the X5 as they stack nicely. The finish with its sandblasted titanium appearance is a bit of an upgrade to the flat black of the original E12. It looks higher end than the original as the buttons are well mated to the recesses and the volume knob is lower profile than the earlier model. While better looking, the knob is not quite as easy to grip due to its smaller size. It should also be noted that the A5 has either chrome plated or stainless Jacks as compared to the copper style used on the E12. I’m not sure if this was a simple cost savings (plated) or a durability improvement (stainless), but I’ll hope for the latter. Either way durability should be improved as the jacks have an outer ring that fits 100% snug to the frame to reduce any possible flex or shift.

Ports are as expected – the top has the volume knob, the 3.5mm single ended (TRS) input and output ports, and the gain switch.

The right side has the micro-USB charging port and the bass boost switch.

Labels are in white on the titanium finish and can be hard to read in some lighting. The left side panel and bottom of the unit are both smooth with no ports. The front face of the amp has 2 LEDs in the top left in line with the input port. The top LED is blue for power the lower is red for charging.


The A5 lists an 880mAh lithium cell battery and has a suggested run time of 12 hours. Based on my tests, I think the suggested run time is reasonable using low impedance headphones without the bass boost circuit engaged. Using 150 Ohm or higher headphones or using the bass boost heavily (although I cannot fathom why you would want to) will result in considerably shorter run times. Either way, once depleted it takes 2-3 hours to recharge using the micro-USB port. This is less than the reported runtime on the E12a but better than the original E12. The only amp in the ones I mentioned initially with better runtime is the PB3 with a rated time of 20 hours and a realistic time of 14-16. It should be noted that the A5 retails for $129 while the PB3 is $199. $70 should buy more than a battery in my estimation but that will have to wait until I have time to review the PB3 to confirm.


The original E12 did well with 50-150 Ohm Cans but was a little too much for sensitive IEMS. Then came the E12a with a lower noise floor, better energy efficiency and better THD, but it lost the ability to power bigger cans. Fiio makes some impressive claims about better power than the e12a (-80mW) and better THD <.002% (1kHz). They also claim to have improved the SNR although hard numbers on this are a bit tougher to come by.

Based on these numbers, I expect the noise floor to be very low even with sensitive IEMs while providing enough power to run 150-300 Ohm headphones. I’ll try my 600 Ohm Beyers but expect they will only be listenable volume at best and not particularly well driven.

First off, the noise floor is indeed as black as expected. The same in ear that had a noticeable hiss when used with the X5iii was perfectly quiet when attached to the A5. With no source connected, I could turn the volume up to roughly 60% before hearing any noticeable hiss. With the Senn HD6xx I could not notice a hiss even when turned up to 100% with no source connected. On the downside, super sensitive IEMS will get very loud very quickly as you turn the volume knob and it will be likely that even on low gain you will have less than 20% usable range on the volume knob. Bottom line, if you have a super sensitive IEM, you are probably better off plugging it directly into the source than into the A5 unless it just needs ridiculous amounts of power.

As for power, the A5 drove the HD6xx well better than the X5 alone and left plenty of room on the knob to increase the power and volume well above the comfortable listening level. The T50rp Fostex was also driven well with less headroom than the HD6xx but still enough to listen at any sane level. The Beyer 600 ohm as expected was not as well driven and while listenable, I had to nearly max out the amp to reach a good listening level and even then, it wasn’t as full bodied a sound as I know the Beyers are capable of. Driving the Beyers also pretty seriously decreased the battery runtime as well which is another sure sign that this was pushing the amp beyond its comfort zone.

The A5 has a mostly neutral presentation with a little warmth. This is not unexpected as the Muses Op Amp is often categorized as being slightly thick in the low-end and perhaps a hint on the warm side. I think Fiio took the natural tendency of the opamp and buffer used and enhanced them slightly to give the amp a bit of extra low-end push and a slightly warm leaning signature. Details are well presented and extension on both ends is quite good. Soundstage is deeper than it is wide although this is common of most portable sources too so it is hard to judge whether the total characteristic is that of the amp or its source. The first thing I noticed was that the treble is a bit forward of where it was on the original E12. Treble extension also seems improved. Not drastically but enough to tell it is there. This gives the A5 a bit more air than the E12. Midrange is well resolved but instrument separation is not spectacular and the mids are mildly recessed when compared to the bass and the slightly forward treble of the A5. The Bass on the A5 is well defined, tight, and well extended unless one enables the bass boost circuit. The bass boost takes too wide a cut as it grabs seemingly everything below 150Hz and amplifies it too much to be reasonable. To my ear the boost bumped the low-end up a good 6db. The bigger problem is that the boost doesn’t return to 0 db until well into the mids. The bass boost creates exactly the situation most of us try to remove: Mid bass hump that bleeds into the mids. Bass-heads may find this wonderful, for the rest of us, I think you will find the bass well composed with the switch off and likely ignore the bass boost circuit entirely as I have chosen to do once I listened to what it did to the sound signature.

Reading this, it would be easy to think this is the most colored amp you’ve ever seen reviewed. I don’t think that is the case at all. It is hard to discuss an amp without specifying its vices as in a perfect world the amp would introduce none of this coloration. All of the coloration I have noted is minor and depending on what source you introduce; the source tendencies will be far more apparent than those of the amp. I used the Schitt Modi2 Uber with my laptop as my source for testing as I am well versed in the signature of the Modi but even at that it can be difficult to determine what characteristics are produced by the amp and what is source or headphone introduced.

Conclusion: The A5 will really appeal to those who want a portable amp to run full sized over-ear headphones, or those with IEMs that require above average power. Those considering the A5 for use with IEMs need to audition the A5 first and know how much of the volume range is going to be usable. Some may find this acceptable, others may find the lack of usable volume control to be a deal breaker. The upside is the A5 is a very well built, good sounding amp with good battery life. In the overall, the A5 seems like a much more refined version of the original E12 with one glaring exception (the bass boost). I would love to see Fiio create a version of the A5 without the bass boost as it does not live up to the quality of the rest of the amp and with a negative gain for use with iems. That way more of the volume range would be usable for IEMs while retaining the ability to power full sized cans.

Pros: Transparency, build quality, value, battery life, output power (superb), low noise floor
Cons: Really needs negative gain switch option for IEMs
For larger (1200x800) images, simply click any photo


Ahhh – the portable amplifier – one of the audio enthusiast's more misunderstood tools / assets. For the beginner, there is the promise of the fabled increase in clarity, details, sound-stage! Once you've been around the traps a while, you learn that careful volume matching takes a lot of these perceived gains away, and you learn that what you thought you were hearing was more than likely the amplified headphone playing slightly louder.
So with today's headphones (especially for portable listening) becoming easier to drive, and people wanting less bulk with their sources (and indeed the sources becoming more powerful), is there any real use for a portable amplifier any more?
I'll try to answer some of these questions from an objective point of view, while walking you through a look at the FiiO A5 amplifier. We'll look at how it performs, and why you might consider one – and what gains you can expect.
By now, most Head-Fi members should know about the FiiO Electronics Company. If you don’t, here’s a very short summary.
FiiO was first founded in 2007. Their first offerings were some extremely low cost portable amplifiers – which were sometimes critiqued by some seasoned Head-Fiers as being low budget “toys”. But FiiO has spent a lot of time with the community here, and continued to listen to their potential buyers, adopt our ideas, and grow their product range. Today, their range includes DAPs, portable amps, portable dac/amps, desktop dac/amps, earphones, cables and other accessories.
FiiO’s products have followed a very simple formula since 2007 – affordable, stylish, well built, functional, measuring well, and most importantly sounding good.
The FiiO A5 amplifier was provided to me gratis as a review sample. I have made it clear to FiiO in the past that I did regard any product they sent me as their sole property and available for return any time at their request. I have purchased quite a few FiiO DAPs and amps over the last 5 years. Recently FiiO informed me that everything they send to me now is a review sample and they will not accept further payment. So I acknowledge now that the A5 I have is supplied and gifted completely free of any charge or obligation. I thank FiiO for their generosity. As a side note – I would have gladly purchased the A5 from FiiO – read on to find out why.
(This is to give any readers a baseline for interpreting the review).
I'm a 49 year old music lover. I don't say audiophile – I just love my music. Over the last couple of years, I have slowly changed from cheaper listening set-ups to my current set-up. I vary my listening from portables (including the FiiO X5ii, X3ii, X7, LP5 Pro and L3, and iPhone SE) to my desk-top's set-up (PC > USB > iFi iDSD). I also use a portable set-up at work – usually either X3ii/X7/L3 > HP, or PC > E17K > HP. My main full sized headphones at the time of writing are the Beyerdynamic T1, Sennheiser HD800S, HD600 & HD630VB, and AKG K553. Most of my portable listening is done with IEMs, and lately it has mainly been with the Jays q-Jays, Alclair Curve2 and Adel U6. A full list of the gear I have owned (past and present is listed in my Head-Fi profile).
I have very eclectic music tastes listening to a variety from classical/opera and jazz, to grunge and general rock. I listen to a lot of blues, jazz, folk music, classic rock, indie and alternative rock. I am particularly fond of female vocals. I generally tend toward cans that are relatively neutral/balanced, but I do have a fondness for clarity, and suspect I might have slight ‘treble-head’ preferences. I am not treble sensitive (at all), and in the past have really enjoyed headphones like the K701, SR325i, and of course the T1 and DT880. I have a specific sensitivity to the 2-3 kHz frequency area (most humans do) but my sensitivity is particularly strong, and I tend to like a relatively flat mid-range with slight elevation in the upper-mids around this area.
I have extensively tested myself (ABX) and I find aac256 or higher to be completely transparent. I do use exclusively red-book 16/44.1 if space is not an issue. All of my music is legally purchased (mostly CD – the rest FLAC purchased on-line). I tend to be sceptical about audiophile ‘claims’, don’t generally believe in burn-in, have never heard a difference with different cables, and would rather test myself blind on perceived differences. I am not a ‘golden eared listener’. I suffer from mild tinnitus, and at 49, my hearing is less than perfect (it only extends to around 14 kHz nowadays).
For the actual listening part of this review I used the FiiO A5 mainly with my X5ii DAP. Observations about the A5 are based on the last four weeks use. This is a purely subjective review - my gear, my ears, and my experience. Please take it all with a grain of salt - especially if it does not match your own experience.
  1. Volume matching was done with a calibrated SPL meter and test tones (1 kHz) when required for comparison.
  2. In the past I have tried to measure distortion using a relatively cheap Startech USB sound-card (which measures pretty well – 0.012% THD and 0.024% THD+ using loop-back). I have stopped trying to do this simply because FiiO's measurements (and I do trust them) are lower than my sound-card is capable of measuring.
  3. Frequency response is measured with the same sound-card and a licensed copy of the ARTA measuring suite. The sound-card has a calibration adjustment applied – so that it measures dead flat from 20 Hz to 20 kHz.
I thought I’d list (before I start with the review) what I would now look for in a portable amp. This is useful to remember when looking at my reasoning for scoring later in the review.
  1. Genuine portability
  2. Good battery life
  3. Clean, neutral signature
  4. Easy to use
  5. Low output impedance
  6. Reasonable output power – should be able to drive IEMs and earphones up to 300 ohms
  7. Good gain control
  8. Value for money
GoVibe Porta Tube, Headstage Arrow 12HE 4G, Beyerdynamic A200p, FiiO E7, E11, E11K (A3), E17K, Q1, VE Runabout. IMS Hybrid Valve Amp


Front of the retail box
Rear of the retail box
Inner box
The A5 arrived in FiiO’s newer style retail packaging – a black outer sleeve with a white main panel and photo of the A5 on the front. The front panel also bears Sony's “Hi-Res Audio” badge. On the rear is a list of features and QR codes. The outer box/sleeve measures 108 x 166 x 52mm.
First glimpse of the A5
Inner packaging / location of accessories
Full package contents
Opening the outer retail sleeve reveals a matt black inner box and lid. This contains a foam cut-out (securely holding the A5), and a secondary envelope and also compartment for the accessories. The accessories include:
  1. 4 FiiO brand rubber stacking bands
  2. 1 x 3.5-3.5 mm micro cable
  3. A USB to mini-USB recharging cable
  4. 2 silicone stacking pads
  5. 1 x cloth carry case/pouch
  6. Warranty and quick start guide
Charging cable and interconnect
Stacking accessories (pads and bands)
Included soft case
The entire package is very practical, covering everything you initially need for the A5. Materials are all good quality. I'd like to make mention of the short interconnect which is ideal for a stacking situation – and also the silicone stacking pads which are ideal for protecting metal surfaces without adding bulk.
The table below lists most of the relevant specifications for the A5. I have also included specs for the original E12 and E12A as a comparison
FiiO A5
FiiO E12A
FiiO E12
~ USD 125.00-130.00
~ USD 125.00-130.00
~ USD 125.00-130.00
124 x 65.5 x 14.5mm
124 x 65.5 x 14.5mm
124 x 65.5 x 14.5mm
Amplifier chipset
Muses02 + LME49600
Muses02 + LME49600
LME49710 & LME49600
Output power (16 ohm)
420 mW (THD+N <1%)
600 mW (THD+N <1%)
Output power (32 ohm)
800mW (THD+N <1%)
880mW (THD+N <1%)
Output power (300 ohm)
150 mW (THD+N <1%)
190 mW (THD+N <1%)
≥115dB (A-weighted)
≥115dB (A-weighted)
≥110dB (A-weighted)
Output impedance
<0.3 Ω
<0.3 Ω
<0.3 Ω
≥ 75 dB (1 kHz)
≥ 85 dB (1 kHz)
≥ 65 dB (1 kHz)
< 0.002% (1 kHz)
< 0.003% (1 kHz)
< 0.003% (1 kHz)
Peak output voltage
14.96 Vp-p
10.3 Vp-p
15 Vp-p
Max output current
250 mA
>113.3 mA
>170 mA
Battery size
880 mAh
1500 mAh
880 mAh
Battery life / Chg time
≥13 h // <3 h
≥20 h // <3 h
≥12 h // <2 h
You'll note a mix in the above specs of the original E12's power, and the E12A's finesse. According to FiiO, they've been able to lower THD by almost 1/3 of the original very quiet E12A, whilst delivering almost the same power as the original E12. So the A5 has a total gain close the the E12, but better channel balance, lower noise floor, and overall a purer, cleaner sound.
The A5 is rectangular shaped with bevelled edges all around, and dimensions of 124 x 65.5 x 14.5mm. The main body is a solid machined block of aluminium, with a top and bottom plate to hold the internals. The finish on the aluminium is a very fine sand blast followed by anodising, and the resultant finish is very clean and smooth.
Top of the A5
Bottom of the A5
USB port and bass boost
At the top are the 3.5mm line-in and headphone out sockets, and FiiO has elected to replace the usual copper socket rings with stainless steel – for better durability, and an added bonus is that it is more aesthetically pleasing. Next to this is the high/low gain switch and then the Alps potentiometer – which has also had a makeover to be more stylish and eye-catching. The action on the pot is very smooth, and I've noticed no channel imbalance even at very low levels.
Line in, headphone out, gain and volume pot
Vol pot is excellent & casine is nicely rounded
Charging and in-use LEDs
On the front face next to the sockets are two small LEDs. One is lit when the A5 is operating, and the second one is lit when charging. The nice thing about the charging light is that it actually also shows what speed its charging at. The faster it's blinking – the quicker it is charging. On the opposite side is a small reset hole.  At the side is the bass boost switch (+5dB at x) and micro USB charging port. I'll show the effects of both the gain and bass boost (and my thoughts on both) later in the review.
Size comparison - X5ii
Size comparison - X7
Size comparison L&P L3
Everything about the A5 is extremely well made, and probably the only critique I would have is a gentle one. The low profile slide switch for the bass boost is (IMO) better implemented than the more prominent “flick” switch for the gain. It just seems a little out of place having two styles of switch – and I'd prefer the bass boost style (consistency and less likely to mistakenly toggle)
I was originally going to open the A5 up and give you a look at the internals – but whilst I could remove the bottom plate, I had no way of sliding the internals out of the shell without knowing the layout. Fortunately FiiO included a photo on their website – so I've used this to illustrate the layout.
Half of the internal space is taken up with the 880 mAh 3S battery, and this uses some pretty smart technology. It will automatically detect the charging rate of your power supply (be it standard USB from a PC, wall-wart, or storage cell), and adjust the rate accordingly for maximum efficiency. I have a battery pack with a 5V 2.1a output, and from flat, the A5 was charged fully in well under 3 hours – not bad considering the up to 13 hours available life.
FiiO's internal photos
FiiO's internal photos
At the heart of the A5's amplification circuit is the MUSES02 + LME49600 op-amp combination which was so successful with the E12A. Other changes FiiO has made include the application of high precision metal film resistors, and the removal of coupling capacitors in the power supply. So what does this mean – in comparison to the E12A? Well for a start FiiO have been able to increase the voltage output (peak is now ~15 Vp-p up from 10.3), and double the max current output (250 mA up from 113 mA), but most importantly they have been able to achieve this extra power with much lower noise output – effectively returning twice as much power with the same or lower noise readings than the original E12A. This is quite a feat.
The A5 boasts two toggle features – the first being a high and low gain switch, and the second being a bass boost. The gain switch does exactly what it says, and lifts the volume by 14 dB under loop-back (no load). The gain is extremely even across the board – and is only adding true volume gain. As I'll allude to shortly – because the A5 is already extremely powerful (without the gain) – I do think FiiO maybe missed out on an opportunity here. If they actually had a negative gain option, it would be better for more sensitive IEMs. The issue at the moment is there is just too much volume available for some IEMs, and unless you are driving extremely demanding headphones, the high gain option isn't really going to be used.
Gain and bass boost - measured
Closer look at the bass boost
The A5 also comes with a bass boost, and the implementation very much reminds me of the bass boost from their E17K. Instead of targeting a narrow band boost, it actually starts a very shallow rise from around 2 kHz and peaks at just under 7 dB around 60 kHz. So this is essentially a sub-bass boost with some effect in the mid-bass, but majority in sub-bass. Engaging it with a reference headphone like the HD600 really helps give some punch and lower end warmth, and with the Beyer T1 it is amazing how it really transforms the overall signature (if this was the base signature for the T1 with bass boost on, I possibly would not have bought the HD800S – yes its that good).
FiiO rates the play time on a full charge at around 13 hours, and recharge time at around 2.5-4 hours (depending on your charger). I've tested it a few times so far, and that range of numbers seems to be pretty accurate, with playtime depending on the load you're driving at the time. What I really like about the A5 though – and I'm considering leaving it permanently attached to the X5ii – is that using it with the X3ii or X5ii line-out extends battery life on both FiiOs by at least 5 or so hours. So if I was going to be on a long haul, or somewhere I simply needed extra life with my DAP, the FiiO A5 would definitely be coming with me.
As usual I’m going to preface this section with my thoughts on reviewing amplifiers. You'll note I don't break this section into bass, mids, treble, and I don't really discuss things like sound-stage or imaging. As you've seen from the graphs, the A5 is extremely linear – it is measuring beautifully flat from 20Hz – 20 kHz. The very slight drop in the sub-bass (about 0.2 dB) at 20 Hz is of course completely inaudible, and if anything I suspect it is my sound-card. So how could I comment on parts of the spectrum if they aren't changed. What you'll hear with the A5 – is simply the signature of the source and the headphones you are using.
Likewise with imaging and sound-stage – there is no cross-feed, so no affect – its just not valid to discuss it as a topic.
What I will say is that the A5 is one of the most linear amplifiers I've heard – a true wire with gain – adding nothing, taking away nothing. Couple that with extremely low noise (the background is beautifully black), and you simply get the music. If you've paired a good source and you're using a good recording, the music will shine. The A5 just gets out of the way. It is what every amp should be.
So how about performance with some real headphones?
Full sized
May as well start with the 600 ohm Beyerdynamic T1. The T1 isn't really a hard to load to drive despite its 600ohm impedance – and the A5 handles it easily. The pot on the A5 goes from about 9 o'clock through to 7 o'clock (it's unmarked – so I have to use this descriptor). On low gain at around 1pm (so about 40% of the pot), I'm at my normal listening level (around 65-75 dB). Pushing the pot to 3 o'clock, and suddenly we're at 80 dB+ and its really too loud. So in real world terms the A5 has oodles of power on tap.
Great with the T1 (+ bass boost)
And the HD800S with no boost
And very good with the HD600 too
But how does the T1 perform? It actually performs pretty well – maybe not quite the amount of bottom end that is exhibited when used with a tube amp like the VE Enterprise, but the T1 sounds truly great. Full bodied, great transients, great tonality. The one thing I can do with the A5 I can't with the Enterprise though is engage that bass boost – and with it the T1 really does hum.
The other two headphones I checked out – again going back and forth between the X5ii + A5 vs the iFi iDSD and Enterprise (same tracks and volume matched) – were Sennheisers HD600 and HD800S. Again (like the T1), the A5 had no issue driving either headphone, and essentially got out of the way – and became a window to the music. With higher impedance headphones the A5 simply shines.
I thought in advance that this could be a very different situation – and likely to be one of too much power on tap. I started with the MEE P1 which definitely need amping (50 ohm impedance and 96 dB sensitivity), and at just under 12 o'clock on the pot, the P1 was perfectly driven. Again the A5 just gets out of the way – and there is no doubt I'm simply hearing the P1's default signature – and its really good.
So how about something more sensitive? Time to try the Earsonics ES3 (32 ohm, 116 dB sensitivity). This time I have the pot right down to about 11 o'clock – and once again I'm pleasantly surprised by how really good the A5 sounds with this IEM (or more particularly how it “doesn't sound”). The background is pitch black, and the ES3 simply shines.
Driving the MEE P1
And the Earsonics ES3
My 64Audio U6 (ADEL) with 75 ohm adaptor
I had the Campfire Andromeda when the A5 arrived (it was due to be returned), so I took the opportunity to try it as well. I was more concerned about hiss and noise floor. Naturally I couldn't hear any – the one advantage of having tinnitus I guess – it masks hiss. But I once again had my daughter Emma (who has amazing 13yo hearing – and listens so quiet that I can barely hear her perfect volume level) to try and see what she could hear. We used the Andromeda with nothing playing and simply raised the volume on the pot. Hiss was faintly audible to her at around 1/3 on the pot, but below that it was dead quiet (low gain). As you've seen above, at 1/3 volume with the Andromeda you'd be blowing your ears to bits with real music (hiss would be the least of your problems) – so the A5 is very, very quiet.
The only issue with the Andromeda was that for my ideal volume – I was very close to the bottom of the pot – and that is the one area I think FiiO could have improved. For the vast majority of IEMs and definitely for most headphones, the A5 is ideal – but for really sensitive IEMs – it may just be a little too much power, and not enough room at the bottom end of the pot. An option for a negative gain would be really handy
Special note (my U6):
So what about my favourite IEM – 64Audio's U6 with ADEL module? Anyone who's followed my journey with 64Audio's U6 (and U10) will know that IMO both simply shine with a higher impedance output – they were initially tuned by 64Audio with higher impedance stage wireless output packs in mind. So with the U6 I often use a 75 ohm buffer impedance jack. This of course makes the A5 a brilliant partner. I can listen around 60-65 dB (I always listen lower with the ADEL module), and on the pot I'm at around 12 o'clock. Another great pairing.
Low noise
I thought I'd finish this section with a couple of graphs – this time trying to measure any distortion. My USB sound-card measures (on loop-back) THD at around 0.011%-0.013% and THD+N at 0.019%-0.020% at pretty much -100 dB if I measure it on loop-back. Its simply not quiet enough to really measure these amps – but its an interesting exercise to perform. So I ran the A5, measuring at 1 kHz and using two different signal – one at 300 Hz and the other at 2 kHz. Both times I was simply recording the USB card's output – the A5 was too quiet to even show up. And the sound-card’s distortion at it's current measurement is beyond real-world audible limits. So I can confirm, the A5 is extremely quiet – even when being pushed at close to full volume.
300 Hz tone - THD measurements
2 kHz tone - THD measurements
FiiO states measured THD+N at 0.002% on their lab equipment, and I have no reason at all to doubt this figure.  The floor is definitely not audible at normal listening levels.
This was a difficult one – how do you compare amp only, when I don't have a lot of portable amps – either in this power bracket, or even in this price bracket?
Because I don’t have a lot of other straight amplifiers at my disposal, I simply used what I had available. So in the end I chose to compare with FiiO's own E17K, the IMS Portable Valve Amp, and my iDSD (even though all 3 are DAC/amp combos). For the comparison I used my X5ii as source, and merely went line-out in each case to the individual amps. I used the X5ii as it's been the main source I've used throughout the review.
A5 vs E17K
A5 vs iFi iDSD
FiiO A5 (USD $130) vs FiiO E17K (USD $100)
Both have very good build and are genuinely portable – the E17K being considerably smaller, lighter. Both have a very neutral signature – essentially wire with gain. Using with the X5ii and volume matched – I really wouldn't be able to tell the difference if blind swapping. In terms of power, the A5's 800 mW output into 32 ohm compared to the E17Ks 200 mW is significant, and the A5 also has almost double the peak voltage output capability. Of course the E17K has a very competent DAC, and also the tone controls (which I love). But for those making a choice and considering both – it comes down to what you are endeavouring to drive. If your aim is to be able to drive higher impedance, or lower sensitivity headphones – then the A5 is the obvious choice. If you're strictly powering IEMs, then the E17K is probably the smarter choice (plus you get the benefits of other features).
FiiO A5 (USD $130) vs IMS Portable Valve Amp (~USD $270 / amp only is ~ $179)
The IMS PVA is actually manufactured here in NZ, and I had the chance to get involved with Martin (the creator) during their KS campaign. The PVA is again smaller in size, and slightly lighter. In terms of signature, the PVA definitely has some warmth to it, while the A5 again simply lets the tonality of the X5ii come through. The A5 has a cleaner background (less noise), and is simpler to use (the PVA does have some issues with overall gain – you can overdrive the valves into distortion with a higher input fixed voltage). Power output is massively in favour of the A5 (800 mW vs 87 mW into 32 ohms). If you're a valve lover, and don't mind the quirkiness of the HVA (with the FiiO DAPs you can lower the line-out volume, and with an iPhone there are no issues), then the HVA is a nice option to have. But for versatility, use with a variety of sources and headphones, and of course the price – the A5 is a clear winner here. I still like both though.
FiiO A5 (USD $130) vs iFi iDSD (USD $449)
The iDSD by now needs no introduction. I haven't reviewed mine yet – but it is my single most used piece of audio equipment. I don't use it portably – mine stays as my main desktop DAC and amp.
Physically the iDSD is heavier and significantly larger. People do use them portably – but for me it is simply impractically large. The iDSD does have a slightly warm tonality, and this was apparent when comparing to the A5. Its not massively coloured – but the difference is noticeable. In terms of power the iDSD wins but its not as large a difference as I expected. In normal mode on the iDSD you can push 950 mW into 32 ohm – but of course you can almost double this using the Turbo mode (effectively a gain switch). But peak voltage (even in Turbo mode) is 8V (about 16 Vp-p) so surprisingly the A5 comes really close – quite a feat for a $130 amplifier.
Of course the real differences are in the versatility of the iDSD (excellent DAC, 3D mode, multiple gain/power settings, ability to be used as a pre-amp etc. But again – if all you need is a portable amplifier to be connected to a competent source, and need strong and clean power output – the A5 is very difficult to go past. The comparison itself is unfair because the two are chalk and cheese – but hopefully it might give anyone with knowledge of the iDSD an idea of how good the power output is on the more diminutive A5.


I’ve now had the A5 for a month, and I'm not really the type to use a portable amp a lot unless I'm really driving high impedance or low sensitivity loads. But I have to admit, it has been great using this combination (X5ii and A5) – so great in fact that I'm thinking of getting some 3M dual lock and semi-permanently melding the two. But I'm getting ahead of myself
The FiiO A5 brings together an impeccable build, good form factor, battery life, and above all a very neutral signature. The utilisation of the bass boost is (IMO) pretty nicely done. But one of the most impressive things about the A5 is sheer amount of power available, and when combined with an extremely low noise/distortion floor – you have an ideal combination for both full sized headphones and easier to drive IEMs or earphones. My one wish would be a negative gain switchable option – just to give a little more play on the pot if using more sensitive IEMs.
When you factor in the unbelievably low $130 RRP, I struggle to think of an amp offering the performance of the A5 for the same or similar price. And when you combine the features fr the price – the A5 gets my unconditional thumbs up and recommendation.
When I look back at my original list of requirements, it has ticked very box – with maybe the exception of the “good gain control”. Its not that its bad – with most head and earphones it is more than adequate – its simply not perfect (yet).
All in all, I would recommend the A5 to both audio starters and the more experienced without question. For what it delivers, it is incredible value for money. 4.5 stars from me.
Thanks once again to FiiO for allowing me the opportunity to review your products.
X5ii with the A5
Size comparison with the E17K
Size comparison with the IMS HVA
Comparative stack size X5ii/A5 vs X3ii/E17K
Comparative stack size X5ii/A5 vs X3ii/E17K
Comparative stack size X5ii/A5 vs X3ii/E17K
Thanks @Brooko for the review, simple and easy to absorb. I pulled plug on A5 myself after reading your review. A noob question how does Balanced of a player works with an A5. one needs a 3.5mm Pin?
Its not a balanced amp - so you'd need to be feeding a single-ended analogue stream to it.
NIce review. The battery is not user replaceable without soldering, as far as I know, no one sells the battery. After 2 or 3 years of use when the battery loses its capacity, you'll end up with an unusable amp. I can't understand why fiio did that... For this reason, it's a no go for me.
Pros: Looks good, feels good in the hand, not heavy, durable, all-metal build, super-low distortion and noise floor, lots of power
Cons: weird gain switch, logo oriented strangely

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[color=rgba(0, 0, 0, 0.8)]FiiO A5 Review: More Power![/color]

[color=rgba(0, 0, 0, 0.8)]Wow, this election cycle has been quite stressful! No matter what side you were on, I’m sure you understand what I mean to a certain degree. Don’t worry though, I’ve got just the thing to take your mind off of it! FiiO recently announced and released a new portable amplifier, the A5. It boasts 800mW of output power, and is good to drive transducers from 16–300 ohms. Not only that, it is built entirely from metal, giving it a durable feel and a premium look. Read on for a more detailed analysis of the A5.[/color]
[color=rgba(0, 0, 0, 0.8)]The A5 can be found on Penon Audio here for $125.[/color]
[color=rgba(0, 0, 0, 0.8)]Disclaimer: This review is based upon a sample unit provided to me by a manufacturer or distributor in exchange for my honest opinion and un-edited words. I do not profit in any way from the writing of the review. I would like to thank FiiO for sending me this review unit.[/color]
[color=rgba(0, 0, 0, 0.8)]Preference and Bias: Before reading a review, it is worth mentioning that there is no way for a reviewer to objectively pass judgment on the enjoy-ability of a product: such a thing is inherently subjective. Therefore, I find it necessary for you to read and understand what I take a natural liking to and how that might affect my rating of a product.[/color]
[color=rgba(0, 0, 0, 0.8)]My ideal sound signature would be an extended sub-bass with a leveled, but textured, bass. The mids should be slightly less pronounced than the treble, but still ahead of the bass. I prefer a more bright upper range.[/color]

[color=rgba(0, 0, 0, 0.8)]Tech Specs[/color]

  1. Weight: 168g (incl. battery)
  2. Dimensions: 124 mm×65.5 mm×14.5 mm
  3. Bass Boost: +4dB (BASS ON)
  4. Drive Ability: 16~300 Ω (recommend)
  5. Battery Capacity: 880 mAh
  6. Battery Life: ≥13 h
  7. Output Power: >800 mW (32 Ω/THD<1%)
  8.  ≥ 150mW(300Ω/THD<1%)
  9. THD+N : <0.002% (1 kHz)
  10. Output Impedance: <0.3 Ω
  11. SNR: ≥115dB (A-weighted)
  12. Crosstalk: ≥ 75 dB
  13. Channel Imbalance: <0.3 dB
  14. Gain: 13 dB (GAIN=H), 0 dB (GAIN=L)
  15. Peak Output Voltage: 14.96 Vp-p
  16. MAX Output Current: 250 mA(For reference)
[color=rgba(0, 0, 0, 0.8)]These specs were taken from the main FiiO A5 thread on Head-Fi.[/color]

[color=rgba(0, 0, 0, 0.8)]Build[/color]

[color=rgba(0, 0, 0, 0.8)]The A5 is built from a generous amount of metal. Everything from the hard aluminum shell to the tactile bass-boost button is made from the stuff, and truly exemplifies skilled workmanship. On the bottom of the unit you can find two Philips-head screws; a rarity in today’s market. After-sales repair should be fairly easy for any DIY-experts out there.[/color]
[color=rgba(0, 0, 0, 0.8)]
[color=rgba(0, 0, 0, 0.8)]On the left face of the chamfered aluminum body you’ll see the micro-USB charging port and the bass-boost switch.[/color]
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[color=rgba(0, 0, 0, 0.8)]On the top you can find the 3.5mm in, 3.5mm out, gain switch, and volume knob. The knob is textured on the sides and has a white line painted on top to allow you to easily discern the current volume of the amp. I would, however, like to make some alterations to the gain switch. This is for purely cosmetic reasons, as I have had no trouble with the gain switch and don’t anticipate any in the future. Currently, the switch is mounted on a swivel joint. That means that it sticks out of the body of the A5 at an angle, something I feel is a bit off-putting. A standard flat switch would be better in my humble opinion.[/color]

[color=rgba(0, 0, 0, 0.8)]Sound Signature[/color]

[color=rgba(0, 0, 0, 0.8)]The A5 sounds clean, neutral, and fast. This is exactly what I look for in an amp, as I generally prefer to color my sound through my source. The noise floor is very, very low on both gain settings, regardless of what transducer I was powering. Not quite black on some sensitive IEMs, but very close to the point where I don’t quite care.[/color]

[color=rgba(0, 0, 0, 0.8)]Performance[/color]

[color=rgba(0, 0, 0, 0.8)]I acquired several finicky transducers specifically to test them on the A5. I really wanted to test the limits of the device to see if it really lives up to FiiO’s rather impressive distortion claims. Present for testing are:[/color]
  1. Macaw GT100s (Sensitivity: 100dB@1kHz, Impedance: 16Ω)
  2. ZMF Omni ( Sensitivity: 92dB @1kHz, Impedance: 50Ω)
  3. Shozy Zero (Sensitivity: 94db@1Khz, Impedance: 32Ω)
[color=rgba(0, 0, 0, 0.8)]For general A/B testing purposes, I also used:[/color]
  1. Meze 99 Classics
  2. Advanced Sound Model 3
  3. Chord & Major 01'16
[color=rgba(0, 0, 0, 0.8)]I had high expectations going into this review, as the A5 makes use of a MUSESO2 + LME49600 combo. That’s some serious hardware. Fortunately, it did not disappoint. The GT100s, an IEM that is very difficult to drive at high volumes due to its low sensitivity and low impedance, performed very well on the A5. The clean output of the device really allowed the IEM to open up its treble and bass, something I’d not yet experienced on my other hardware.[/color]
[color=rgba(0, 0, 0, 0.8)]The Omni performed well. If I really wanted to listen to something LOUDLY, I needed to switch to high gain. Startlingly, however, I could not hear any distortion, roll off, or clipping in high-gain.[/color]
[color=rgba(0, 0, 0, 0.8)]I chose the Shozy Zero, not because it is hard to drive, but because it is very picky about what source it is powered off of. Turns out it really does get along well with the A5, more so than when powered straight out of my AP100.[/color]
[color=rgba(0, 0, 0, 0.8)]The A5 lasted almost 13 hours on my trial (on low gain at medium volumes), which is almost exactly the length quoted by FiiO.[/color]

[color=rgba(0, 0, 0, 0.8)]Accessories[/color]

[color=rgba(0, 0, 0, 0.8)]In the box you will find:[/color]
  1. 4x Rubber stacking straps
  2. 2x Rubber spacers
  3. 1x Cloth carrying pouch
  4. 1x 3.5mm to 3.5mm cable
[color=rgba(0, 0, 0, 0.8)]All in all, I’m very satisfied with the accessories that came with the A5. Given it is only an amp, I’m not sure what else they could have reasonably included, and all the things that came inside the box feel high quality and work well.[/color]

[color=rgba(0, 0, 0, 0.8)]Summary[/color]

[color=rgba(0, 0, 0, 0.8)]The A5 is a very good amp for the price. FiiO combined impeccable style, a durable build, and impressive internals, all for what is a reasonable price given the A5’s competition. While some users may have wanted to trade the A5’s high output levels for longer battery life, I find that my DAPs generally die before the A5 does. Thusly, I recommend it to anyone looking to step up their mobile amperage game. Good job FiiO.[/color]
@Dobrescu George Thanks for the compliments and suggestions! I'd really like to add more to my Sound Signature section, but I genuinely cannot hear a non-negligible and consistent coloration of change in sound when using the A5. Therefore I consider it disingenous to add more to that section simply for the sake of adding. Perhaps if I were reviewing a tube-amp where there is a lot of room for change in sound I would consider expanding the section. I will, however, add an analysis of Bass Boost mode soon.
Is it transparent?
@Headzone Are you asking if you can "see" into the sound when you listen? If so, then yes. The A5 is essentially unnoticable on the majority of my earphones and headphones. Some of my more finicky earphones do gain a more expansive sound stage and experience some slight changes in frequency response, but they are the exception, not the rule.


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