in ,

Not Bronze Age ; MAS Audio Science X5i IEM Headphones

Pleasing features

When you take these MAS Audio Science X5i headphones out of the box what strikes you is their great build quality. The stitching effect on leather or leather effect covers around the drivers. Headphone cords and leather – that sounds like a recipe for an entirely different product type altogether, but I digress….

But it’s surprising for In Ear Monitor (IEM) headphones at this price, that you get all of this. Also the acoustic chambers have a nice stand out anodised bronze finish. They look like proprietary machined bullets that may only be used in a specialised high powered firearm. My mind went to the Bond film, The Man with the Golden Gun. You don’t carry them around in cigarette packets in a sinister fashion, like in the film, but probably in the supplied soft pouch.

It’s exciting then that they may sound as good as they look? We often find this with a total attitude to design; when designed well in appearance they are designed well for sound too.

MAS Audio Science X5i headphones
MAS Audio Science X5i : Tasteful Bling – leather stitched with bronze!

The silver coated copper twisted pair cable has the usual 3.5mm socket with a coil end to protect the cable. At the other end each IEM is detachable from its connector of the MMCX type. Tremendous as you could try other cables too. Any an audio lover knows, silver cables can really help with the high frequencies and the supplied ones are up to task.

These IEMs are quite big, but in use I didn’t find any issues with them popping out. Out of use they clip back to back under their magnets.

MAS Audio Science X5i detachable earphones
MAS Audio Science X5i : Detachable cables

In the stout presentation box there is also a remote cable for use with mobile devices, which is of lesser quality to the silver coated copper one. It has a microphone for calls and an inline Mic button to reject and take calls and operate Siri on iPhones, for example. You get a selection of ear tips as well.

The X5i’s are described as having “5 drivers for each IEM – a dynamic driver and 4 balanced armature drivers”

I was also given a MAS Audio Science XX USB-C cable for use with a supported device and a XX Bluetooth cable. The Bluetooth cable has a USB charging dock and a USB to micro USB cable is supplied to charge it with an iPhone charger or similar.

The XX USB-C Cable contains a Digital to Analogue Converter (DAC) to simulate surround sound effects when listening to movies or when gaming, which is turned on or off by the Mic containing inline controller. Unfortunately I was unable to try it not having a supported product, one of which is an Apple iPad Pro.

MAS Audio Science accessories
MAS Audio Science X5i accesories

Sound impressions?

I initially used the X5i’s in a marvel system comprising a Chord Qutest DAC, Yamaha WXC-50 streamer and a JDS Labs Atom Amp. The Qutest is one of the most resolving DACs at this price and with the quality of amplification I would expect this test system to get the very best out of these headphones.

They are a considerable step up from the sub £100/$100 class, like some cheap as chips Sennheiser CX-400 II headphones I have lying about which are thin sounding and lacking. Undoubtedly against Apple earphones too, which are messy with and lacking articulation, in bass. But the X5i’s shouldn’t be this price. Quite ridiculous really for them to charge such an amount. I was actually astounded and shocked…….This is because they should be priced higher! But let’s whisper – we don’t want MAS Audio Science hearing I said that. The articulate balance and tone are definitely a nod to pricier IEMs.

Using the Audio Science headphones with Chord Qutest, Yamaha EXC-50 and JDS Labs Atom
MAS Audio Science X5i : Yamaha / Qutest & Atom pairing

I’m impressing the notion here that spacious and airy treble should be in the mind when auditioning headphones. It has a habit of annoying some people after a while, whilst sounding shop-floor brilliant to start with. The X5i’s achieve a bit more than this with great balance. They are neutral, rich and refined but with necessary treble when needed which isn’t in your face. The bass is well extended too.

The problem with headphones that try and create a huge soundstage by extending treble, is that they can do so at the expense of trading balance. Trying some Final B3’s (£439) and Campfire Audio IO’s (£300) recently, they project music in this way and don’t have the balance of the X5i’s. It makes these MAS Audio Science headphones a very hard act to follow at the price and because of this balance it makes them natural headphones. I think their appeal will be very wide.

I fell in on chance with being offered these headphones, and I’m glad of the chance as they are little gems. They certainly sound as good as they look. So far as the step up in quality over budget offerings, it’s a no brainer and I can wholeheartedly recommend taking the step. It might be hard for some to stomach paying £300/$300 for something so small, but when you see their quality and hear their sound, it’s worth it.

MAS Audio Science X5i with periodic audio Nickel headphone amp and FiiO X1II
MAS Audio Science X5i : Periodic Audio Nickel Headphone Amp with X5i headphones & FiiO X1II music player

Used into an iPhone with their best cable, with no outboard DAC or headphone amp, they keep their impressions up. Albeit with the sinking compression and flattened dynamic effect of iPhones. I found this is improved using a £300 Periodic Audio Nickel headphone amp which doesn’t include a DAC. It simply allows you to plug in headphones via a 3.5mm socket with another 3.5mm cable diverted to your phone. It charges extra detail and depth to these headphones, as they are working more efficiently. Allowing more insight at lower volume too. I’ve no idea what the iPhone output is but you are getting approx 250mW from the Nickel into these headphones.

X5i headphones with AudioQuest DragonFly Cobalt
You won’t clock watch with this pairing : X5i with new Audioquest DragonFly Cobalt into iPhone SE

Trying them with the new Audioquest DragonFly Cobalt with an Apple ‘Lightning to USB 3 Camera Adapter’ into an iPhone SE, which is necessary to accommodate the USB socket of the Cobalt, all their qualities are maxed out further.  An added shot of resolution and warmth makes for an impressive combo. They seem to match the DragonFly Cobalt well because this mini headphone Amp/DAC behemoth is well rounded too and not too incisive or edgy with treble, unlike a Cyrus Soundkey for example. It brings the detail out in a natural way which suits the X5i’s.

I’ve never got Bluetooth unless you are engaged in sweaty pursuits and don’t want cables flapping about. This is because Bluetooth is obviously a compressed format and it degrades sound quality and what hassle is a dangly cable anyway? With the XX Bluetooth Cable it’s not so much ‘Blurtooth’ since the sound is clear and has quite good detail. It’s just there isn’t the same richness and bass qualities as using the best cable, as you might expect. This is nothing new and not a criticism of the product, just the limitations of Bluetooth. You do get the usual volume up and down controls and facility to answer your phone with inline Mic.

These X5i’s are equally a dab hand if using portable hires music players and to this end I also tried an inexpensive FiiO X1II (£100) to good effect. They also work really well with an iPod Classic. However if used portably, you really get the best out of them when using the best box supplied cable in conjunction with something like the DragonFly Cobalt. These headphones aren’t as good alone with the Cobalt as they are when using the Nickel and Cobalt together, unsurprisingly. But the combination has everything for IEMs – headphones to die for.

MAS Audio Sciene X5i and AudioQuest DragonFly
MAS Audio Science X5i : With the AQ DF Cobalt and Nickel Headphone amp

I also tried the X5i headphones with the DragonFly cobalt as the pre-amp. Rather confusingly the Cobalt can be both a pre amp and power amp, but don’t worry about how this happens. The effect is you can use a 3.5mm to 2 RCA cable from the Cobalt, to your headphone amp. I used a cheapish Audioquest Evergreen cable.

Don’t be put off by the fact MAS Audio Science may not be as well known as some other headphone brands. The X5i’s are an absolute steal, relating their sound and build quality against price. They definitely achieve the 13th note and come very recommended! I love them.

Various set ups with these headphones
AQ DF Cobalt into AQ Evergreen cable into the Atom Amp, is an impressive combo
MAS Audio Science X5i : Check out my film here. I also look at the Audioquest DragonFly Cobalt & Periodic Audio Nickel


Driver unit : one 10mm Dynamic + 4 balanced Armature
Impedance – 12 ohms
Frequency Response – 5 to 70,000hz
Sensitivity – 105 dB/mW (@ 1 kHz)

XX Bluetooth Cable**
Bluetooth 4.2
Operating Freq – 2.4GHzOperating Freq – 2.4GHz
Distance Range – 10m
Play time – +12 hours
Standby time – approx 150 hours
Charger – USB DC 5v

XX USB-C Cable**
Sample rates and both depths : 384khz / 32bit, DSD 256
SNR : 105dB
THD+N : -101dB
Input : USB type C
Output : MMCX
MEMS digital Mic


Headphones : $300/£300
XX Bluetooth Cable – not published?
XX USB – C : $99/£99
(**Available via Amazon)

Manufacturer Details

Website :
Contact :

Sibling – MAS Audio Science X5h over ear monitors

Written by Simon Price

I'm music lover who shares experiences of faithfully reproduced audio in an ENGAGING way with HIGH VIDEO PRODUCTION VALUES. I enjoy and make reviews as I love audio gadgets, being a voice on audio and producing creative videos that ultimately benefit the industry and new participation. I keep technicalities easy, as I believe great audio serves music and music is inclusive and to be enjoyed by all!

Periodic Audio : Carbon IEMs and Nickel Headphone Amp

KEF : A Factory Tour