ISN Audio Rambo Earbud Review











ISN Audio Rambo Earbud Review



ISN Audio is a Chinese brand that is producing earbuds and cables for In-Ear Monitors.

The ISN Rambo which I will know review is the first earbud model of the company.

ISN Audio Official Website:




I would like to thank ISN Audio for providing me this sample via Penon Audio for review purposes. I am not affiliated with ISN Audio and Penon Audio beyond this review and these words reflect my true and unaltered opinions about the product.




The ISN Audio Rambo is available on Penon Audio for 65,00 USD under the link below:

Purchase Link:



Package and Accessories:

The ISN Audio Rambo is coming in a small rectangular cardboard box that features illustration and product brandings.

The box is containing the following items:

  • 1 piece x ISN Audio Rambo
  • 6 pairs x foam Tips
  • 1 piece x Zipper Case
  • 1 piece x Karabiner



Design, Fit and Build Quality:

The ISN Audio Rambo has a lightweight plastic shell that shares the same design language of the Shozy or Yuin erabuds.

On the top of the ISN Rambo earbud are two air channels and the left/right markings.

The ISN Audio Rambo is featuring a woven cable with a grey plastic coating.

The cable sports a chin slider and a metal Y splitter with Rambo branding.

The ISN Audio Rambo has a straight profiled headphone jack with a 3.5mm TRS (unbalanced) connector and a metal housing in black color.



Technical Specifications:

  • Driver Size                 : 14.8mm
  • Frequency                  : 6-25 kHz
  • Impedance                 : 32Ω
  • Sensitivity                   : 115dB
  • Plug Type                   : 3.5mm/2.5mm
  • Cable Length              : 1.2m



The ISN Audio Rambo has a relative low impedance of 32 ohm and a sensitivity of 115dB. This values making the Rambo to an easy to drive earbud that works efficient with most smartphones, tablets and audio players with low amplification.



Equipment’s used for this review:

IEM’s              : ISN Audio Rambo, TY Hi-Z F300M, Hifiboy Dream
DAP&DAC’s  : QLS QA361, Cayin N5II, FiiO M3K, Astell&Kern SR15


Albums & tracks used for this review:

  • Leonard Cohen – You Wnt it Darker (Spotify)
  • Dave Gahan – Kingdom (Tidal Hi-Fi)
  • Eric Clapton – Wonderful Tonight True (Flac 24bit/96kHz)
  • First Aid Kit – My Silver Lining (Spotify)
  • London Grammar – Interlud (Live) (Flac 24bit/44kHz)
  • Laura Pergolizzi – Lost On You “Live at Harvard and Stone” (Tidal Hi-Fi)
  • Vivaldi – Le QuarttroStagioni “The Four Season” (Tidal Hi-Fi)
  • Alboran Trio’s – Cinque Lunghissimi Minuti (Tidal Hi-Fi)
  • Otto Liebert & Luna Negra – Up Close “Album” (DSF) – Binaural Recording
  • Lorde – Team (Flac 24bit/48kHz)
  • Massive Attack – Angel (Tidal Hi-Fi)
  • Portishead – It Could Be Sweet (Spotify)
  • Liquid Tension Experiment 2 – Acid Rain (Spotify)
  • Opeth – Damnation (Tidal Hi-Fi)
  • Metallica – Sad but True (Flac 24bit/96kHz)
  • Megadeth – Sweating Bullets (Tidal Hi-Fi)


The Sound:

The ISN Audio Rambo is an earbud with a slightly warmer than neutral tonality, which has moderate bass quantity, a lively and pretty transparent midrange and a clear well extending treble range.


Please note that the sound performance of earphones may vary from user to user as the fit and ear anatomy greatly affects the overall performance.



The ISN Audio Rambo has a fairly analytical and linear bass presentation with a neutral tonality.

The Rambo’s subbass shows less emphasis than those of the midbass region. The subbass has moderate depth and intensity which is not very ideal for genres like pop, electronic, rnb etc. while acoustic tracks are enjoyable.

The main focus in the lower frequency region is the midbass area which shows sufficient quantity, intensity and speed. The detail level is on a god level and there are no negative situations such like muddiness or bass bleed.

I would advice you to pair the ISN Rambo with sources which have a warmer and thicker tonality.




The midrange of the ISN Rambo is the star of the show with its detailed vocals.

It has a close to neutral tonality and sounds, slightly bright, transparent and fairly detailed. The midrange is not too laid back or to upfront and is showing a pretty natural balanced presentation.

 The ISN Rambo is successful with both male and female vocals. The general presentation of vocals is quite spacious and airy with good detail rendering for the price. Female vocals are sounding lively, clean and pretty emotional due to the well emphasized upper midrange tuning, while the male vocal performance is good but not that impressive compared to female vocals.

ISN Rambo’s instrument tonality is close to neutral, a bit bright and is showing a touch of warmness. It is missing some lower midrange depth and thickness which is needed for instruments like the contrabass and guitars.

The general presentation is very spacious, clear and transparent that makes the separation of the instruments pretty easy, while the positioning is quite good for this price range.



Upper Midrange and Treble:

The ISN Audio Rambo has an emphasized but controlled upper midrange presentation. It sounds quite detailed in this area for a $ 65 earbud and is showing also good extension. There is no unnecessary harshness or any sharp spikes.

The ISN Rambo’s treble range has a slightly bright tonality and is sharing a nice amount of sparkle. The treble extends pretty well and makes it successful while listening to genres like jazz or classical music. The ISN Rambo shows also a good level of clarity and definition for a earbud at this price range.

The treble intensity and sharpness of the Rambo is quite well tuned without to show any unwanted sibilance and harshness.




The ISN Audio Rambo has a nice “out of the head” presentation and is showing a good performance in terms of instrument/vocals placement and separation. The soundstage is quite spacious and airy, while it is showing more wideness than depth.



Some Comparisons:


ISN Audio Rambo versus TY Hi-Z F300M

The TY Hi-Z F300M shows more subbass depth and quantity compared to the ISN Audio Rambo which lacks a bit in this area. When it comes to the midbass, the TY Hi-Z F300M shows slightly more intensity and quantity, while the ISN Rambo has the upper hand in terms of control.

The midrange of the TY Hi-Z F300M sounds slightly warmer and fuller than those of the ISN Audio Rambo. The ISN Rambo is more successful with female vocals due to the more natural and transparent presentation, while the TY Hi-Z F300M has the upper hand for male vocals due to the fuller and more emotional tonality.

The upper midrange of the ISN Audio Rambo is superior in terms of speed and control.

Both the Rambo and the F300M are quite successful earbuds when it comes to the treble range. The ISN Rambo sound in general more natural and controlled in this area, while the TY Hi-Z F300M is a bit sharp and is prone to sibilance.

Both earbuds are showing a nice out of the head presentation. The soundstage of the TY Hi-Z F300M has better depth, while the ISN Audio Rambo is slightly better in terms of soundstage width.




ISN Audio Rambo versus HiFi Boy Dream

The HiFi Boy Dream has a noticeably warmer and thicker tonality than those of the ISN Audio Rambo.

The subbass of the Dream shows more depth, quantity and rumble, while the Rambo has slightly better control. The midbass of the HiFi Boy Dream have more intensity and slightly better extension compared to the Rambo erabud.

The midrange of the Hifi Boy Dream sounds warmer, thicker and shows more depth. The ISN Audio Rambo on the other hand has a brighter, cleaner and thinner presentation. Female vocals are more lively and realistic with the ISN Rambo, while the Hifi Boy Dream is the better choice if you are listening to male vocals.

The ISN Rambo is superior in terms of upper midrange extension and detail, while the Hifiboy Dream is a tad more controlled in this area compared to the ISN Rambo earbud.

The treble range of the ISN Audio Rambo shows a bit more definition and clarity and sounds slightly more airy and with sparkle as well. The HifiBoy Dream, on the other hand, is characterized by a gentle and fatigue-free presentation that makes it ideal for long listening periods.

The soundstage of the ISN Audio Rambo has slightly more width, while the both are close in performance in terms of soundstage depth.




The ISN Audio Rambo is the first earbud experience of this company, but has a quite mature tuning. At this price point, it’s makes up for its light bass with a detailed sound and each note has good definition. The clarity and airiness of the midrange and the well tuned treble range that sound pretty detailed and fatigue free will impress many earbud lovers.



Pros and Cons:

  • + Clarity and transparency
  • + Midrange tonality and detail
  • + Treble extension and control
  • + Fit and Comfort


  • – A bit bass shy
  • – Cable is prone to intertwines
  • – Soundstage depth


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