The ISN Audio EST50 was kindly provided free of charge in exchange for an honest review. I didn’t receive monetary or any other kind of compensation and I don’t use affiliate links. The price of the ISN Audio EST50 is $449 and you can buy it from Penon Audio.
ISN Audio EST50
ISN Audio is an earphone and cables manufacturer distributed by Penon Audio. A brand virtually unknown to me until I had the opportunity to review the ISN H30 which proved surprisingly well sounding and aroused my curiosity about their flagship IEM. The ISN EST50 is a hybrid earphone that uses 2 Sonion Electrostatic drivers for the ultra-high frequencies, 1BA Knowles for high frequencies, 1BA Sonion for the mids and a 10mm dynamic for the bass.
Build quality and appearance
The lightweight ear-shells have a design that is pretty much identical to that of the ISN H30. They feature an anatomical shape and are made from a skin friendly resin compound. They are a little bulky when compared to single driver earphones but the mildly extending sound tube and the semi-custom design helps a lot with the fit which is stable and comfortable even after prolonged time of use while they effectively block environmental noise.
The faceplate has a beautiful wood grain pattern with the ISN logo engraved at the center of it and is available in two colors, stabilized wood orange and green. Build quality is simply excellent.
Cable
The ISN EST50 features a 1.2m detachable cable with 2-pin 0.78mm connectors and you have the option to order it with either 3.5mm, 2.5mm or 4.4mm termination plugs. The truth is that at this price point a modular cable would be a better and more competitive offering. Thus said, the braided cable is of good quality, it is super lightweight and soft without microphonic noise and it doesn’t get tangled.
Accessories
The ISN EST50 comes with two sets of silicone ear-tips in three sizes each, two pairs of memory foam ear-tips, a cleaning brush, a shirt clip and a premium looking, high quality, hard carrying case with a magnetic lid. The presentation box is a little bare bones and not as luxurious as someone would have expected.
Power requirements and associated gear
The ISN EST50 is rated at 18Ω/100dB so it doesn’t have much requirements for power but it really responds well to higher quality gear. I have mainly used the iBasso DC04PRO, the Cayin RU7 the FiiO M11S and Penon Tail. As per usual practice the ISN EST50 was left playing music for about 100 hours before listening evaluation.
Listening impressions
Fun and exciting, the ISN EST50 has a tuning with a tasteful bass emphasis without letting down the rest of the frequencies. The dynamic driver can reach deep enough to the lowest notes, rewarding the listener with a subwoofer experience. The sub-bass isn’t overpowering so the mid-range and treble stay clear and defined enough. The bass is emphasized, especially in the upper part of it, as a result is not that well suited for critical listening. Timpani will sound more overpowering than they should and double basses or cello are rendered slightly out of tune. Of course there is much more than classical and the tuning of the ISN EST50 low-end is perfect for listening to rock, metal, electronic and other kinds of similar music where a hefty, but not dominating, bass is desirable and adds plenty of excitement. The ISN EST50 is very dynamic and impactful, the bass is visceral and weighty although not that well controlled. Definition and layering are satisfying but the bass is slightly on the slow and relaxed side.
The mid-range is superb, tonally balanced and accurate, articulated, well defined and crystal clear. The timbre is natural and realistic with plenty of harmonic variety, everything sounds lifelike and engaging. Voices, female especially, are heavenly good. The ISN EST50 has a musical and present mid-range which sounds good with everything. The transition to the treble is smooth without any fatiguing upper-mids emphasis, making the ISN EST50 the ideal choice for people with sensitivity to this particular area.
The treble is easy to the ear with an aristocratic politeness but without lacking in extension and excitement. The EST50 is not the most brilliant or sparkling sounding earphone but still there is plenty of light and enough energy to keep things moving and well contrasted to the low-end so the sound is not excessively warm or dark. The Sonion drivers add a great portion of resolution and refinement, the treble is of the highest quality, it is full bodied and decays in a relaxed manner. Tonality is quite accurate so all instruments sound realistic without artificiality while electronic tunes are not piercing or fatiguing.
The five drivers are really well integrated so the overall sound signature is very cohesive without any weird tonal shifts or audible frequency discontinuities. The ISN EST50 is quite open sounding with a solid center image and excellent stereophonic panning. The truth is that it doesn’t sound too holographic or proportionally layered but it offers sharp imaging and plenty of air around the performers.
The ISN EST50 wouldn’t be my first choice for critical listening to classical music but it gave really great moments and much enjoyment with classic rock and metal bands like Guns N’ Roses.
Compared to the Dunu EST 112 ($489)
The DUNU EST 112 is a hybrid earphone with a driver configuration that resembles that of the ISN EST50. One large, 13.5mm dynamic driver for the bass, a Knowles BA for the mids and two Sonion EST drivers for the high and ultra-high frequencies. The well designed earshells are made from aluminum and offer a comfortable wearing experience without protruding outside the ear. The Dunu EST 112 comes with a high quality modular cable with three plugs, three different types of silicone ear-tips (spinfit included), a pair of memory foam ear-tips and a nice carrying case with a side zipper.
The Dunu EST 112 has a rather balanced tuning with more neutrality in the bass, great presence of the mid-range and a treble that is definitely more emphasized, sharp and less forgiving than the ISN EST50. If the ISN EST50 represents the casual and fun oriented earphone then the Dunu EST 112 is it’s reference and critical sounding counterpart. The bass is more imposing and impactful, the larger driver moves more air while it manages to stay fast, tight and controlled albeit not as visceral and full bodied as in the EST50. The mid-range is lusher and warmer in the ISN EST50, a little more musical, with a weightier texture and less biting in the upper mid-range. The treble is smoother and more forgiving in the ISN EST50 while maintaining excellent resolution and refinement. Equally refined and resolving is also the Dunu EST 112 in the higher frequencies but it is slightly sharper, brighter and more energetic sounding than the EST50 with faster transient response. Two good sounding earphones of the mid-range category with slightly different sound profiles to cater for individual listening habits.
In the end
The ISN EST50 has a deliberately casual tuning with plenty of well realized bass, present mid-range, well defined treble and great technicalities so it is well suited for listening to all kinds of music as long as there are no critical requirements. It is musical, exciting, engaging and responds well to upstream gear. Well made and very comfortable, it is highly recommended but it would be a much better value if it had a modular cable.
Copyright – Petros Laskis 2023.
+ Great sub-bass extension + Plenty of well emphasized bass + Dynamic and impactful + Musical and engaging mid-range + Smooth and refined treble + Good technicalities + Spacious soundstage with precise imaging + Easy to drive and scales well + Comfortable and lightweight + Good passive noise attenuation + High quality cable and carrying case + Excellent build quality - Not suitable for critical listening - Bass is a touch slow and not that well controlled - Bulky ear-shells that extend out of the ear - A modular cable would add better value
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