TouchMyApps » MST All Things iPhone and iPad for those who like to Touch. iOS App reviews, News, New Apps, Price Drops and App Gone Free Fri, 03 Jul 2015 01:57:21 +0000 en-US hourly 1 MST FiQuest headphone amplifier and Cio MB DAC in Review Mon, 15 Oct 2012 03:40:37 +0000 Two years ago, boutique manufacturer MST rocked headfi by teaming up with iBasso to create what was arguably the highest quality portable amplifier on the market. Getting one required some patience as MST are a small outfit with a few employees. Their FiQuest, which has been upgraded in the year 2012, is better than ever. … Read more]]>

Two years ago, boutique manufacturer MST rocked headfi by teaming up with iBasso to create what was arguably the highest quality portable amplifier on the market. Getting one required some patience as MST are a small outfit with a few employees. Their FiQuest, which has been upgraded in the year 2012, is better than ever. In this review, TouchMyApps will be looking at two versions, plus a small optical DAC.

FiQuest-2012-ciomb-iphone FiQuest-2012-family-ES10 FiQuest-2012-iPhone-next FiQuest-2012-iPhone-top FiQuest-2012-powercontrol FiQuest-2012-volume

Build quality
As you can expect from a Japanese outfit, things are put on straight. The FiQuest is less a portable amp than it is a transportable all-in-one portable/desktop replacement amp. The FiQuests large battery keeps it humming for 7-10 hours depending on load and usage. Because of its size, and because of its designer, ergonomics – as they apply to a transportable amp – are very good. Point number one: the in and output ports (all metal affairs) are spaced perfectly. No matter how large your headphone and input cables are, they will fit. And the ports are anchored well into the board and into their niches on the amp’s faceplate.

MST use slide switches for bass and gain rathe than knobs or flick switches. Considering that the FiQuest is primarily a transportable amplifier (and ostensibly not subject to the same amount of bumping as small amps are), the slide switches may be overkill. Small amp makers should take note: flip switches are easier to break, MST chose right. And, overkill that protects one’s investment is always good. In fact, it’s excellent.

The on/off switch is a flip switch, but it is a shallow-trunked affair that is as likely to break as I am to get that pay rise I’ve been begging after for years. Good for the FiQuest, rotten for me.

The one item that bothered me two years ago bothers me still. It’s the thin-pitch bolts that fasten the front and back plates to the chassis. If you’re in the habit of frequently and haphazardly opening up your FiQuest, eventually you will strip the bolts. I guarantee it. So be careful. The FiQuest is a joy open and dink around with. In fact, it is so customisable that it almost begs you to dig and dig. Just make sure you use good tools and don’t cock your hands at hard angles.

Ergonomics and Polish
As I hinted at above, ergonomics are damn good. In fact, despite being such a beast, the FiQuest is quite simply one of the easiest to use amps. It’s not just the switch panel layout or the spacing of the in and output ports. It’s the heft, which balances easily in the hand, never too bottom nor too top heavy. And even at low volumes, great balance is achieved from the large, smooth volume pot.

This is the FiQuest I remember. And it is wonderful.

Charging functions are on the back, and again, implemented via slide switches. The power supply is chunky, but so is the male jack and pin on the FiQuest’s bum. You won’t break it. Again, small amp makers with chintzy plugs, take note. This is the way to ensure you have fewer hardware malfunctions.

Apart from that, though, MST’s amp really is a straightforward metal brick. Fitting it into the pocket of any trouser is not recommended. It is simply too big. While I find the array of in/out ports very good, I’d like the output to be 6,3mm, not 3,5mm. Ryuzoh said the FiQuest is primarily a portable amplifier – a fact I well understand – but so is the GoVibe Portatube+. A 6,3mm jack just simplifies the use of other headphones.

Next, neither gain nor bass settings are labelled. You have to find your own way with the FiQuest, or just listen to me. Right is start, left is end. MST are Japanese. Keep that in mind.

Late night Music fans, the lamp on the FiQuest will not brighten your room like the sun like Vorzüge’s amps do. As great as they are, the Vorzüge amps are in dire in need of circumlision (in case my language is too deep for you, that’s the combination of circumcision and light, meaning nothing less than circumcision of light. How’s that for professional writing?) MST’s lamps are understated, more so even than ALO’s masterpieces, if that were possible. And believe it or not it’s pink. Damn. And I thought MST had grown up.

I’ll start this off reiterating how good the FiQuest volume pot is. It is the best I’ve used among portable amps of any price. Balance is perfect. And because the FiQuest has three levels of gain, low really is low. If you are using this monster with earphones (and trust me, there is good reason to), you will have no problem achieving left/right balance. If you are using it with headphones that need either lots of voltage or stamina (which some people call current) you are in luck.

Just as it did two years ago, the n FiQuest features a bass boost. It’s understated just like it was back then. It amplifies up to ~3,5 decibels. You will hear it, but you won’t be blown out of your seat. You want to know its polar opposite? Vorzüge.

Gain settings are gregarious: 0dB, 9dB, and about 20dB. Medium and low gain settings enough for any headphone out there, and because they impact signal quality very little, are most recommended. High gain is like the 230km/h top speed limit on your minivan’s speedometer: it makes you look like a badass in front of your kid’s popular friends, but is best left untested.

Which brings me to sound.

Two years ago I had one reservation: IMD errors forced at loud volumes from low ohm earphones. MST rectified the issue in a hardware release. If you have the first or second or third batch, you might opt to send your amp to MST for a tune up.

Today’s models need nothing so much as a willing ear, and a thick wallet. Now, there are several models to choose from, each offering slightly different sound. I’m sure MST would argue with me on this point, but this is MST’s baby. I’m a hardened reviewer with calloused ears. Small differences faze me like a mosquito phases a space shuttle.

That said, I can definitely see that the different flavours will appeal to different users.

The Accuro-bat
While there is no such word, there is a gaggle of amps that follow what I feel is the purest audiophile dictum: neutrality. Among powerful portable amps, MST’s FiQuest is a strong fighter. Its signal is clean, lean, and never damns itself by stepping where it shouldn’t. While its size sets it apart, sound-wise, the FiQuest almost completely disappears.

But it’s not just signal neutrality and authority that advertise MST’s latest opus; its the FiQuest’s coy noise signature, and resolution. This amp is powerful enough to whip the Audeze LCD-2 into shape, yet gentle enough to handle a FitEar To Go! 334. Noise simply doesn’t enter into the FiQuest’s picture in the way it does MST’s desktop-replacement competition. And resolution is extremely high, yet somewhat cozy.

Even engaging gain and bass boost does very little to harm the signal. There is no deleterious noise anywhere. That said, of course you will have less background noise in an amp like a Pico Slim, but then again, target headphones for each device are completely different. Among desktop replacement amps, the FiQuest is the trump card, and I am impressed.

The midrange is full of springy energy. Acoustic guitars resonate with pure, fast attack; decay is speedy and frontal, displaying its meaty underbelly to the ear. On low and medium gain settings this presence is as clean as clean can be until the volume is pushed too high. If you need extra oomph, choosing the next gain setting is your best bet to retain the same fidelity. Again, I recommend low and medium gains.

Sound in a nutshell
MST employ neither low nor high pass filters in their amps. Their bass and gain circuits play kindly both with the most sensitive of earphones and voltage-hungry cans.

The FiQuest’s father, Ryuzoh, assured me that my favourite headphone, Beyerdynamic’s DT880, would require the best spec and best parts to sound best. The poor lad needn’t have worried. The DT880 is driven so well by any flavour of FiQuest that I simply have to chuckle at the semi-worried face he had before I put my recommendation behind the combination.

The only proviso is that if you are stupid enough to play your DT880 600Ω at ultra-high volumes when fed from weak sources, you should keep move the gain up rather than maxing volume on low gain. Overall, overhead is high; at normal to medium-high volume settings, every earphone/headphone performs without flaw. But when passing 90% on the volume pot in low gain and whilst under load, the FiQuest spits out moderate levels of distortion. The audible effects are debatable since at those volumes, your eardrums are likely to collapse rather than delightedly hammer away to your favourite tunes. But for the sake of pushing an honest review, I’ve got to say it.

The FiQuest is as powerful at full volume as the Centrance DACmini PX. Surprisingly, ALO Audio’s The Pan Am is quite a bit more powerful with the likes of the DT880 600Ω. Of course, the Pan Am doesn’t play as well with earphones like the FitEar To Go! 334. And, when I say ‘power’, don’t misinterpret it for ‘pleasure’. At those volume levels, it’s your headphones or ears that will be destroyed.

There is no way this side of hereditary hearing loss that anyone would need anything more than a FiQuest to drive their DT880 of any ohm rating and sensitivity to deafening levels. More impressive to me is that the sensitive TG334 is driven equally authoritatively.

That brings me to this conclusion: despite its general coy indifference to whatever is plugged into its output, the FiQuest delivers truly excellent resolution all the way along the frequency path. I know that its tight, smooth treble will gain fanatics. Its bass is surely in for the same fate.

The bass gain settings go up in baby steps: less than 3 dB on gain 1, and just over 3dB on gain 2. This maturity is borne of dedication. MST’s house sound is resolving with energetic midrange and excellent reach in both treble and bass. Bass holds more texture than treble, which, for a solid state amp, is intimate and forgiving. Sibilant earphones and sensitive ears may find the FiQuest’s grainless treble presentation indispensable. Indeed, this box is a powerful, portable alternative to a high-class valve amp.

Scaling with better sources
There’s no need to ask. Yes, the FiQuest amp is capable of meeting your system. Feeding it from an iPod or Walkman will reveal most of what it is capable of, but stepping up to a Cypher Labs CLAS or CD player will only reveal more. Herein lies a question: with such power and resolution and the ability to scale from source to source, why doesn’t the FiQuest have RCA inputs? I’d love to plunk it down in my HiFi system connected via RCA cables. Assuming that the analogue input section is implemented well, channel separation and noise should improve even further with RCA input over the current 3,5mm input.

But, the FiQuest is a portable amp. RCA inputs seem right out of place, don’t they?

Best headphones for the FiQuest
I’ve sung some pretty high praise for this amp. And overall, it deserves it. While the FiQuest plays no real favourites with regards to what is plugged into its output, take a look at it. It’s huge. And powerful. And looks like a skinned wireframe extrusion. It really fits a desktop better than it does a pocket or bag.

Medium-high headphones are close to perfect. There are no checks in my spirit warning me to suggest to LCD-2 and K701 headphone users to suggest a different amp. The FiQuest is about as good as it gets – that is, as long as you are using a strong line-level output and keep the volume below 80% and stay away from the high gain setting.

Sensitive high Ω headphones like the DT880 600Ω and the FiQuest are somewhat of a mixed bag when run from equipment like naked Apple iDevices. To avoid distortion, use a Cypher Labs CLAS and apply the gain settings liberally. But, that is only if you tend to listen to insanely loud volumes. At normal listening levels, the DT880 is an excellent friend to MST’s amps.

Ryuzoh plugs custom earphones into his FiQuest and hangs the stack from a cool leather belt at his side. He’s hardcore. I’m not. But I’ve met many hardcore portable audiophiles like him out there. For them, there may not be a better portable amp to connect to custom earphones when on the go and to power full-size headphones at home. The FiQuest has more power, more control, and a uniquely fine-tuned bass gain circuit that enhances the lows for any headphone out there than any rival in its class. The fact that it is done maturely is a testament to MST’s devotion to quality rather than quantity. In short, for custom IEMs and high-end universals, the FiQuest is perfect. If you are after the largest soundstage and super-detailed treble, there are slightly better options on the market. If you love the resolution of solid state amps, but sometimes find treble to sometimes be painful, take a look at the FiQuest.

The Cio MB DAC
How cute is this little box? Just like the one I tested a few years ago, this is a high-performance optical DAC that works well with a MacBook Pro, Go-DAP X, Go-DAP Unit 4.0, and Fostex HP-P1.

It’s tiny. It’s battery lasts for up to 10 hours. There are small optical cables on the market. Everything seems in order for it to take its place at the top of great portable systems -that is, except output volume.

Its line out is underpowered. Plugging it into a HiFi or external headphone amp will reveal less pressure than an iPod or iPhone. Indeed, it steps down more than 10 decibels from the output of an iPod line out.

But, its signature is lovely. There is very little interference that gets into and out of the box. The sound is laid back, smooth, hearkening back to CD players of old. Connected to the FiQuest, it makes you want to curl up with favourite jazz CDs and knock back a bottle of wine.

Is performance isn’t aimed at better-than-16-bit like the CLAS; rather, it exerts soft control over the entire gamut of metrics, toning here and prodding there until even the harshest recording sings in engaging, mellifluous accents. I recommend it for lovers of NOS parts, valves, and vinyl. It is a digital piece that injects a little analogue magic into a system.

On the flip side, if you gauge DACs by absolute resolution, no matter how brittle, the Cio MB isn’t for you. Stay with the CLAS.

Gain – unlike its mature bass settings, gain settings are aggressive. An approximate 9dB gain in medium position is quite a jump. The high gain performs like a proof-of-concept rather than a real feature. Sure, you’ll get loads of extra volume at high gain, but you’ll obviate some of what makes the FiQuest so special. Resolution remains high, but dynamic range is compressed slightly. Interestingly, the DT880 600Ω and FiQuest on high gain at any comfortable listening level remind me very much of the Pan Am. I love the Pan Am, but the two are very different beasts with very different audiences.

Volume DAC – the Cio MB is a wonderful product in a small, sturdy package. A battery-powered DAC is most welcome. But its output is quite low. Even an iPod outputs more SPL into a headphone amp. Paired with the FiQuest, you’ll have to bump gain quite high with headphones like the DT880 600Ω, and move the volume pot into somewhat dangerous territory.

Volume FiQuest – despite offering enough (in fact, more than enough) volume to any headphone out there, the FiQuest does so with less precision than it should. Maxing out any volume setting reveals more distortion than necessary. And of course, there is the maximum gain setting, which I feel is unnecessary. Features for the sake of features are sometimes better left out.

3,5mm only – this is a portable amp. Ryuzoh reiterated this many times in our conversations. It is a wonderful portable, but it can replace bulky mains amps, too, and works wonders for a large majority of full-size headphones. I know I am not the only one who wishes it came with a full-size 6,3mm stereo phono plug. This isn’t an issue; it’s an observation. But, it’s a pointed observation about an amp that deserves the full monty.

The FiQuest would be the perfect amp if it weren’t for its somewhat mild volume issues.

I actually published this review about a month ago, but for some reason left it private. Such tardiness is unpardonable. But in the meantime, I’ve had the chance to discover the Pan Am, another intriguing desktop replacement amp.

In terms of resolution, the two carry on in two very different ways; the Pan Am goes the way of warmth and intimacy, while generally, the FiQuest attacks from the perspective of resolution. Interestingly enough, the Pan Am’s absolute volume ceiling with hungry headphones such as the DT880 600Ω is quite a bit higher. At such volumes, it suffers comparatively less distortion, too.

But, the FiQuest is easier to finely tune, and runs the full gamut of headphones from the likes of custom earphones to the mighty DT880, better overall. But, because of my private publishing boner, I can add the following addendum:

The FiQuest is the 2nd most powerful portable amp I’ve used for full-size headphones.

MST run an uncompromising business. For just about every headphone out there, their amps are overkill – and that is a good thing. It’s better to start out from a position of strength. The FiQuest boasts excellent resolution and volume balance. And wonderful bass circuitry. Its lows and mids attack with energy and resolve with fine detail. Treble is ever so slightly forgiving. Indeed, this is an amp for custom earphones and high-end universals. It is an amp for high-end full-size headphones, too. MST have come a long way and despite a few polish niggles, deliver one of the best amps at any price.

Excellent resolution
Excellent volume balance
Lots of power
Good ergonomics
Taught, energetic sound

Unlabelled sound controls
Test-mode style 3rd gain setting

Hot damn! Headphones really are a rockin’ way to enjoy music, right? Feel free to explore TMA’s headphone oubliette

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MST Audio supporting Red Cross Japan with proceeds from Red Tide sales Wed, 16 Mar 2011 12:30:35 +0000 I’ve been following #Japan on Twitter since the horrible earthquake and corollary tsunami last week. Among the myriad voices, the Japanese audiophile community has been rallying support. MST Audio, maker of the fabulous FiQuest headphone amp, will be donating 32% of the proceeds from their new, limited edition Red Tide interconnect cable, to the Japan … Read more]]>

I’ve been following #Japan on Twitter since the horrible earthquake and corollary tsunami last week. Among the myriad voices, the Japanese audiophile community has been rallying support. MST Audio, maker of the fabulous FiQuest headphone amp, will be donating 32% of the proceeds from their new, limited edition Red Tide interconnect cable, to the Japan Red Cross. Red Tide uses 15cm long CV4.2 cabling from AudioQuest and will hook up your iPhone/DAC to a headphone/car/home amp. Red tide will cost 95$ of which, 30$ will be donated to the Red Cross. Cables should be ready to ship out one in April. Since many of Japan’s supplies are constrained after the devastation, only 50 of MST’s Red Tide will be made. Shipping information is as follows:

ASIA:$12; Oceania and Northern America:$15; Europe:$18; Southern America and Africa: $20

Via first class international
ASIA, Guam & Saipan:$4.5; Oceania, North America & Europe:$5.5; South America and Africa: $6.5

Purchasing will be handled through MST’s sales account:

MST Audio are located in Tokyo and have seen first hand the devastation wrecked by the earthquakes and tsunami. They’re a nice bunch of lads who have their ears on one thing: audio perfection, and their hearts in the right place. Thank you MST!

NOTE: Watch this post for information on where to sign up for Red Tide.

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FiQuest headphone amp in review – Adroit audio evangelism Tue, 04 May 2010 08:06:13 +0000 If you aren’t ready to take the wild walk on the DIY side, but still want to really get down and dirty with tweakable headphone amps, there are a very few options available to you. One of them is to experiment McGuyver style with cotton, fish, cookies, and an oiled grouse to achieve a truly … Read more]]>


If you aren’t ready to take the wild walk on the DIY side, but still want to really get down and dirty with tweakable headphone amps, there are a very few options available to you. One of them is to experiment McGuyver style with cotton, fish, cookies, and an oiled grouse to achieve a truly experimental sound. But if lock picking DIY isn’t your thing, there are only a few choices on the market. Some such as Graham Slee, Firestone, iBasso, etc., offer headphone amps with user-replaceable op-amps and slightly modifiable circuits, but no one outdoes MST, a one-man operation out of Akihabara Japan. MST’ FiQuest project is as ground-up tweakable a design as is possible in a pre-fabbed design. In a way, it is the audio evangelist among portable amps.

Feel free to discuss the FiQuest in our forums.

Power Source: Rechargeable 12-series Ni-MH Battery pack
Frequency Response: 5Hz – 100kHz/ -0.5dB
Gain: +3dB/+12dB/+23dB
SNR: 109.7dB (Gain:L), 101.2dB (Gain: M), 96.1dB (Gain: H)
Crosstalk: 90.7dB
Total Harmonic Distortion+Noise:
0.0009% @1kHz/+12dB/1Vp-p/600Ohm,
0.0011% @1kHz/+12dB/1Vp-p/100Ohm,
0.0018% @1kHz/+12dB/1Vp-p/33Ohm,
0.0024% @1kHz/+12dB/1Vp-p/15Ohm
Maximum Output power:
1300mW+1300mW (12Ohm loading+External powered),
590mW+590mW (12Ohm loading+Internal Battery Powered),
Battery Life: 8 Hours (with Maxxed config.) to 20 Hours (Normal)
Battery Charge Time: 2.5 Hours
Recommended Headphone Impedance: 8-300Ohm

Build and Package
If the first thing that strikes you when you see the FiQuest is its size, you ain’t blind: it is BIG. In fact, portable amps don’t get quite … this large. For that reason, the FiQuest transcends the ‘portable’ world and ascends to can be loosely dubbed: ‘transportable’. It IS at home in very large pockets, backpacks, and purses, but does an equally good job atop a HiFi or a desk.

Like Graham Slee’s Voyager, size comes with a number of advantages, mostly build quality and ease of use. The FiQuest is a high-quality platform for the tinkerer. Nearly everything on the inside can be custom-ordered, and from a DIYer’s usability standpoint, it earns accolades. Everything from the volume pot to the power supply is easy to fiddle with and replace. Heavy, yes. Fiddley, not at all. And of course, it is strong. The FiQuest’s walls are machined from ~3mm thick extruded aluminium with as little lateral flex as a cryogenically treated body builder.


To open it up, you need a hex key and the ability to discern between clockwise and counterclockwise; to have fun, you just need tweezer-like fingers and a few op-amps. Thankfully, MST can supply you with the latter. This amp is designed to be tinkered with.

There is one concern, however, with the FiQuest’s design. The four bolts that hold the front and rear panels on will go through a lot of twisting. If you go DIY wild, eventually, they will strip the aluminium casing. In that case, I recommend replacing them with static bolts and thum-screws.


Features in Review
Things get really sick from here on in, and by sick, I mean ‘amazin’. Firstly, under the bonnet is a powerful battery supply and recharge circuit. The maxed version is rated for up to 8 hours of use while the normal version eeks out 20. The truth is that the maxed mode can actually play music for a little more than 9 hours. Considering the power under the bonnet, this spec, while trite in comparison to a long-running amp like the Graham Slee Voyager, is respectable.

The real DIY bit, however, comes from the fact that every op-amp in the amp is user replaceable. That means the main L/R op-amp(s), buffers, and ground channel amps can be changed to your liking. What that means for the end-user is many possibilities. It IS true that op-amps have very low distortion, and that on paper, most shouldn’t differ that much. But in an amp, powering very different circuits, the swap of a single op-amp can mean the difference between good sound and great sound.

I’ve settled on the simple combination of: BB OPA2111KP in the L/R socket and BUF 634P in the Buff channels. This combination affords me: very low levels of hiss and smoothly detailed mids with low end punch. It drives everything from my super-sensitive FitEar 333 to my gory 600Ω DT880 with the energy and overhead of a busload of zombies.

You can easily tinker it for max power or max finesse. But perhaps the most important DIY feature of the FiQuest is that its case can stay off whilst the amp is being overhauled. I’ve used a LOT of headphone amps and really enjoyed passing op-amps in and out, and on occasion, soldering here and there. For simple op-amp switching, having to reassemble, replace, and re-cap everything is Oprah-book-hour boring. With the FiQuest, if I want to make a quick change, I do it with ad-hoc expedience.

Note: remember to shut the power off when fiddling with the FiQuest’s insides.


I noted that the Graham Slee Voyager was one of the best if not the best portable amp I’ve heard for driving my rather finicky DJ1Pro headphones. The GSP amp has got loads of power and a house sound that deepens the bass even without the contour switch engaged. Well, the FiQuest follows suit: it packs punch for hard-to-drive headphones, and for easy-to-drive headphones, supplies plenty of volume and control.


I ordered the Maxxed version as per my desire to really push a lot of hardware and I’m glad I did. Despite splashing out up to 16V, and driving the 600Ω DT880 to nearly ear-splitting volumes, the FiQuest is beautiful for any variety of inner earphones and iems.

Firstly, channel balance is extremely tight. For reference, I’ve re-seated the volume pot to point to 0 at the letter v on the volume legend. With a twist to the letter o, it is perfectly balanced on my most sensitive IEM’s and reveals no static when adjusting. Of course, every pot will vary slightly, but even sensitive ears should be able to enjoy low-volume amped music. Moving up to any proper headphone, especially high Ω beasts such as the DT880 is of course, better. There is no channel imbalance even at the lowest of discernable volumes.

The 600Ω DT880 can be very quiet from a lot of sources, but at high gain on the FiQuest, they double perfectly as desktop speakers. There is no better layman term to describe the power that belts forth other than: OMG. Of course, since I don’t need another operation, I never twist the high gain volume past about 12 o’clock.

Another issue with a lot of portable amps is radio interference. The FiQuest possesses no special powers, but its thick case does reflect most noise. I don’t know if I am just lucky, or if the FiQuest is just really well battened-down, but I’ve yet to grab someone’s mobile phone call – shame that.

So, how does it sound? Well, that is the hardest part to describe. You see, it sounds how you want it to sound. I suggest hashing it out with MST before purchasing. I wanted a do-it-all, and that is what I got. But MST can tailor an IEM-ready FiQuest if you want, or a power-hungry DJ1Pro FiQuest for you.

With my headphones, the FiQuest re-invents a lot of sensuous listening experiences. After I discovered the magic combination of op-amps, it took over as my home IEM amp simply because it is grain and for the most part, relatively hiss free. Of course, with any sort of proper headphone, there is NO hiss at all.

At normal listening levels, the maxed FiQuest is an IEM dream. It pushes through deep resolution, for 95% of hard-to-drive balanced armatures, perfect treble resolution. Dynamic earphones are easy breezy for the FiQuest: control, width, power, and extension.

The bass toggle adds up to 3dB of bass in three steps. Most bass boosters add 8-10dB, often creating murky messes in favour of a thump. The FiQuest’s circuit, on the other hand, is subtle. What isn’t subtle is its handling of the DJ1Pro, a headphone that ‘responds’ well to different amps. Its 64Ω isn’t ‘hard to drive’ in terms of volume. Instead, its voice deepens depending on the output source. Amps that can pump out a lot of voltage tend to bring out more bass from the DJ1Pro’s speakers. The FiQuest falls in that camp: lows belt out in ferociously smart aural earthquakes – earthquakes which violate everything when the bass toggle is engaged.

Moving up to high Ω headphone such as the HD600 and DT880 is beautiful. There is plenty of volume, space, and overhead, and in default bass configuration, the FiQuest is neutral. There is very low distortion, so don’t expect your knife-edged 600Ω DT880 headphones to suddenly sprout the dark, smooth voice of the HD600. That really is the beauty of the FiQuest – it preserves the headphone’s original voice. Assuming you like your headphones, you’ll love the FiQuest.


The one issue I’ve sussed with the Maxed FiQuest is intermodulation. Certain low Ω earphones can force intermodulation into the signal that is especially evident at high volumes. It isn’t an op-amp related problem as I’ve tested many configurations back to back with the same issue. Most earphone do NOT force intermodulation, and it only occurs at volumes which would deafen a rock star. Among my earphones, only one causes this distortion: FitEar Private 333; and among my headphones, only the DJ1Pro at high volumes.

One other small issue is ON/OFF thump. The FiQuest is not loud as the ALO Rx or the Graham Slee Voyager, but there is a noticeable surge, so be careful to keep earphones out of your ears when turning the amp on.

Chart Disclaimer
This review’s RMAA measurements reflect the performance differences between the naked iPod touch 2G and the same iPod when paired with the FiQuest maxed and ALO Cryo line out dock. Since they are taken with my equipment, they should not directly be compared to other technical data. The data represents the ability of the amplification circuit to drive headphones. It is NOT the headphone response data.

RMAA Charts for the FiQuest are found in the forums.

Sound Conclusion
The FiQuest is a powerful beast of a portable amp that does every job well. It isn’t limited to IEM’s or to headphones. You will get great frequency response from it with even the hardest to drive earphones such as the FitEar Private 333, but it is even more at home with headphones like the 600Ω DT880. Because it is buttons-to-bottom configurable, its sound is hard to pin down. But, I can say that your money isn’t going into distortion – it is going into a powerful wire-with-gain amp. The one area that needs improvement with the current Maxed FiQuest is intermodulation with lowΩ earphones and headphones. While intermodulation doesn’t affect normal listening levels, it is audible, and isn’t brought out by my other amps.

So the ~349$ – 449$ question is: is the FiQuest worth it? For those who want/need a transportable desktop amp, it is. There really isn’t anything readily available that fits the requirements of both IEM’s and headphones. The combination of resolution and very low hiss makes it a great desktop IEM amp, but with the simply flip of its gain switch, it is transformed into a voluble amp for any headphone. Since it can be configured to your specifications, it is more ‘your amp’ than any other headphone amp on the market. MST has done its homework – at least mostly. Everything is easy to use and sounds great with the exception of intermodulation distortion. That fixed, the FiQuest will for myriad uses, be the most holy amp on the market.

MST FiQuest Summary
Title: FiQuest Developer: MST
Reviewed Ver: Maxed: for FitEar 333 and DJ1Pro: op-amp numbers:
  • OPA211
  • AD744JN
  • LT1028ACN


  • 634
Connection: Stereo Mini 3,5mm
Price: $350-450 Application: Portable/transportable
  • Excellent construction with good RF rejection
  • Easy to tweak
  • Great, linear sound
  • Lots of sound options available
  • Small ON/OFF thump
  • Intermodulation distortion
FiQuest can be ordered in June from MST Audio – more information to come

Headphone amps and DACs help your headphones get the most out of their transducers. Take a look through our headphone section for suggestions of good upgrade/sidegrade options, and our headphone amplifier section for suggestions on how to wring out the best performance from your beloved phones.

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