FATfreq x Effect Audio: Quantum

Here it is: “Quantum”, the brand new product line from FATFreq and the first model with the same name. The new IEM is priced at 766 USD, just above the Scarlet Mini. This new Quantum was developed in collaboration with Effect Audio, a cable manufacturer. The Quantum itself was of course designed by FATFreq. However, it was matched with the Ares S II cable from Effect Audio, which is included in the scope of delivery. Tonally, the Quantum series takes a different approach to the Maestro series, which is more V Shape tuned, towards a more neutral and accurate playing style.



The Quantum is equipped with a Planar Magnetic driver that was developed for a year until it met the requirements. Feedback from audiophiles and studio engineers has been taken into account to achieve a sound signature that satisfies audiophiles and whose sound quality can also be used in the studio.

With the Quantum, there is no need to worry about implementing crossover networks, as there is no need to keep multiple drivers synchronized. The Planar Magnetic driver covers the entire frequency range from bass to treble. Planar Magnetic drivers are known for their outstanding bass response, extremely natural midrange and precise high frequencies. Although many drivers can have peaks in the treble range. FATFreq has counteracted this with an acoustic system called “ResoFlow”, which uses a very precisely tuned resonator to achieve a smoother high frequency response without compromising detail and airiness.

The tuning of the Quantum can be changed using the NOAH modules supplied. The brand new SuperStage module, which is used in the flagship Grand Maestro, is also on board. The black and blue NOAH modules are also included, so that three different tunings can be realized.



Let's start with the scope of delivery. The unboxing experience is rather unspectacular. The included utensils such as the storage box, the silicone ear tips and the cleaning brush are familiar from other IEMs and are standard. The focus here was mainly on the IEMs and the cable. And the Effect Audio Ares S II is a wonderful cable! It is the world's first hand-braided 8-core IEM cable. It combines two different types of copper, which should result in improved low bass and a stronger bass kick. At first glance, the Quantum looks different from the competition. At first I thought, would it be comfortable? How wrong you can be! It really is one of the most comfortable IEMs I know. Because it doesn't protrude deep into the ear canal, it can be worn for several hours without any problems, without anything pinching or getting in the way. In combination with the AZLA Xelastecs, it isolates and fits me perfectly. I also like the sound best with these ear tips. The workmanship is first class. The metal finish, the scratch-resistant underside, the fit and the design look futuristic and the Quantum really is a real eye-catcher.

For the sound test I used the iBasso DX340, once solo and once in combination with the D16 DAC and PB5 Korg Tube amplifier. Like all FATFreq IEMs, the Quantum likes power, so I sometimes have to engage the second gain stage depending on the recording. However, I think this is an advantage over the IEMs, which are very easy to drive, because you can control the volume much better.



The Quantum was designed with absolute precision and control in mind and you can hear that from the first notes. This is not the typical FATFreq signature that I know from the Grand Maestro, Scarlet Mini or Deuce HBB. The Quantum is fast, very fast! It is a tuning that is more energetic, more neutral with less bass range compared to the Grand Maestro and especially the Scarlet Mini. But by no means too little bass! The sub bass goes way down into the basement and the mid-bass kicks hard when it's needed. This is the typical Planar Magnetic bass that I only know from my Audeze LCD-4. It also goes down into the basement at breakneck speed with a lot of texture and you can literally feel its mid-bass attacks even without a BCD. A Scarlet Mini has more bass, but not the control and speed of the Quantum. This is the best bass I have ever heard in the price range up to 1000 USD!

The mids are still very precise and controlled. The separation is at a very high level and the vocal reproduction is very natural. You can directly hear the timbre between a Planar Magnetic and BA drivers. The Quantum simply sounds “different”, not better or worse. It's a bit like switching from a Focal Utopia 22 to a Hifiman Susvara. You can hear these more romantic, slightly sweeter mids in a direct comparison. The Utopia 22 or a BA driver, on the other hand, seems a little more technical.

The high frequency response is very good, although the Quantum can't quite keep up with the IEMs that contain 4 EST drivers or more. Fortunately, I don't find the peak at 8Khz annoying. Either I'm not very sensitive here or the “ResoFlow” system from FATFreq is doing a very good job. In general, the high frequency range comes across to me as very well resolved without appearing flattened anywhere in its extension. The Quantum also produces a very open and airy sound.

The stage presentation with the SuperStage modules is brilliantly airy and very spacious. Well above average in this price range. For me, this is also the most balanced presentation overall and these NOAH modules are my favorites. With the black modules, the Quantum sounds a little more direct with more volume in the sub bass range. However, the Planar Magnetic driver always remains under full control and retains its fast bass attacks. If you want to feel even more mid-bass kicks, you can use the blue modules. These emphasize the mid-bass somewhat more than the sub bass. However, both modules do not come close to the SuperStage modules in terms of spatiality and separation. In terms of airiness, they are also a league above. I assume that the larger volume of the modules makes this significantly greater imaging possible. Even if they protrude from the IEM, they have no effect on comfort. They also don't increase the weight particularly, as they are as light as a feather.

I really like the Quantum on the DX340. My sound descriptions above were also based on operation directly on the DX340. If you switch to the complete iBasso chain DX340 + D16 + PB5, the Quantum plays with an even more powerful bass range and slightly fuller mids. The spatiality also increases somewhat. This is the crème de la crème in combination with the Quantum. But even with the DX340 I don't miss anything if I don't make a direct comparison. However, the Quantum should be accompanied by a powerful DAP, because it needs considerably more power than other IEMs.

In my opinion, FATFreq has achieved a great success with the Quantum series. Never before have I heard an IEM with a single planar magnetic driver that delivers such brilliant sound quality. FATFreq has also proven that they can achieve more neutral tonalities and how! For me, a welcome change from the Grand Maestro when things need to be more accurate and neutral. Metal, EDM, Rock - all modern genres sound absolutely great with the Quantum. The bass range is unrivaled in the 1000 USD class and the soundstage is also at the top level in this class. With its absolutely coherent and precise reproduction, the Quantum is perhaps the IEM for anyone looking for their endgame in this price range! Well done, FATFreq!