FIR Audio M5 (pre-production)

*** Review of M5 with a final production tuning is HERE ***


PROS: smooth natural tonality, strong bass impact, tubeless hybrid design (DD/3BA/ESTAT), ATOM module (internal or removable), choice of FIRCON or 2pin connectors.

CONS: price, universal not available yet (but coming soon).

The product was provided to me free of charge for the review purpose in exchange for my honest opinion.

Manufacturer website: FIR Audio.  Available for sale directly from FIR Audio or Music Sanctuary.


Making its debut at CanJam SGP ’19, FIR Audio just unveiled a brand new addition to their product line, custom IEMs in various multi-driver (balanced armature, dynamic, and electrostatic) configurations (price of Universals, when released, will be the same as Customs below):

  • m2 – dual BA: BA low-mid, BA hi-mid ($499)
  • m3 – hybrid DD/2BA: DD low, BA hi-mid, BA high ($899)
  • m4 – hybrid DD/3BA: DD low, BA mid, BA hi-mid, BA high ($1399)
  • m5 – hybrid DD/3BA/ESTAT: DD low, BA mid, BA hi-mid, BA high, ESTAT-high ($2199)

When I reviewed their headphone VAC last year and then had a chance to test their custom cables, I didn’t realize those audio accessories and other tools introduced under FIR Audio brand were just teasers while Bogdan Belonozhko (CEO, founder) and his team were cooking something bigger in their lab.  And for those who are not yet familiar with FIR Audio, I’m sure many will recognize “Belonozhko” name and their very driven band of brothers who have been involved in designing and manufacturing of IEMs for the last decade under 1964 Ears turned later into 64 Audio.

FIR Audio was founded last year (2018) by Bogdan as a separate company, and the name comes from Fir Trees, a type of evergreens common to Pacific Northwest region of Washington state, not a coincidence since the company is located in Vancouver, WA.  If you look closer at their logo, the “I” in FIR is shaped like a fir tree, though there is also a logo of rabbit eating a corn on their headphone VACs which I believe has its own story behind it.  But regardless of the name, the logo, or the legacy, the focus of this review is on FIR Audio brand new flagship m5 hybrid IEM I had a chance to test over the last week.  So, let’s find out more!


Unboxing and Accessories.

m5 arrived inside of an aluminum round jar with a twist off lid and a replaceable dehumidifier container attached to it.  The jar has a removable soft foam lining to protect IEMs during shipping, while the dehumidifier pellets container is intended to remove the moisture from IEMs.  It’s not exactly a pocket friendly travel case, but quite functional for luggage storage while traveling and using it as a portable dehumidifier.  The top of the jar lid had FIR Audio logo/label and my “Twister6” name which I assume could be customized by request when placing the order.


The provided accessories included a set of foam eartips, a cleaning tool, and a small leather strap with a snap-on button to organize the cable.  Keep in mind, this is a universal 3D printed demo of their Custom IEM, thus a reason why eartips were included.  Obviously, don’t expect to see it with your CIEMs.


Another optional accessory I received was FIRCON to 2pin adaptor.  It will certainly come in handy if you order FIR Audio monitors with FIRCON connector and would like to use it with your 2pin cables.  The pigtail adaptor was long enough to comfortably fit over my ear; just remember that many aftermarket cables have a pre-shaped flexible earhook so it won’t attach straight, unless your cable has a memory wire or no earhook.  Keep all these options in mind since you do have a choice of ordering FIR Audio IEMs with either FIRCON connector or a regular 2pin.



Since this is a new product launch and I didn’t get a chance to use FIR Audio IEM designer, I don’t know exactly the level of cable customization yet, but I’m quite familiar with FIR Audio own custom cables which you can read more about on their Cable page.  I was told there will be black, clear, red, and blue FIRCON connector color option, and black and clear wire jacket color option, as well as different terminations with various balanced and single ended plugs.  For IEM connectors, only FIRCON and 2pin will be available for now.

My review unit arrived with 8-conductor matte black SPC (scorpion wire) cable, terminated with 4.4mm BAL plug, black custom y-split and a matching chin-slider.  At the IEM connector side, no memory wire or earhook was used, going straight into the housing of FIRCON connector (w/a proper L/R labeling) with short strain relief.  The wires are very supple, with a soft rubbery black jacket, inner twisted in 4-conductor bunches for Left/Right sides going above y-split, and each bunch twisted again going down to the gold-plated 4.4mm balanced plug with aluminum housing and carbon fiber insert.  Overall, the cable felt very strong and durable, and non-microphonic.


I’m sure many will be curious what is this FIRCON connector all about.  It’s a new type of IEM connector which kind of reminds me of mmcx since you are not dealing with two separate pins and don’t have to worry about the polarity.  But at the same time, it’s different from mmcx, especially since the base of the connector is squared, interlocking when mated to prevent rotation.  The mating parts of the connector seem to be durable and feel secure when snapped together, and according to FIR Audio those are rated up to 5000 insertions.  In theory, you will get less wear and less room for dirt to get inside.


2pin connectors are still dominating IEM industry and they are considered to be more reliable than mmcx since the cable doesn’t rotate, causing to lose contact or to get specks of dirt inside.  But 2pins and their sockets could have tolerance issues when dealing with aftermarket cables, can loosen up after a while, and you have to pay attention to polarity.  FIRCON, like mmcx, just snaps in without worrying about pin polarity and its square locking design prevents it from rotation.

Just my personal opinion, but I think many audiophiles who enjoy cable-rolling and already invested into 2pin premium cables will probably go for 2pin connector option.  Or maybe they will try FIRCON to 2pin pigtail adaptor.  It’s really hard to change audio industry “standards” overnight, but I do want to give FIR Audio credit, at least for trying, and I think musicians who want a more reliable cable connection will appreciate this change from the get-go.  Otherwise, only time will tell.


Page 2 – Design and Sound analysis.

Page 3 – Comparison, Pair up, and Conclusion.

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