For Astell & Kern AK240 Digital Audio Player

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The RWAK240 is a modified version of the Astell & Kern AK240 digital audio player (DAP):


When comparing the headphone output (both the SE and BAL outputs) of the AK240 to some of the best dedicated, portable headphone amplifiers, it becomes apparent that the AK240 lacks in bass impact and extension.  While the AK240 bass is nimble, it is missing foundation and authority when called upon, especially with lower impedance headphones.  There is also some missing body.  The main reason for this has nothing to do with output voltage swing or output impedance.  It entirely has to do with the fact that the power supply rails for the headphone output stages are quite low on reservoir capacitance, so they have a hard time delivering the needed instantaneous current that high-end, dedicated portable amplifiers can deliver.  Inside the AK240, space is very limited and there isn’t the room for a respectable amount of power supply rail capacitance if it is to be installed on the board as needed for mass production machine assembly.  Fortunately, there IS a way to hard-wire increased capacitance directly to the rails of the output stage FETs by way of the modification process, and this is exactly what is done with the RWAK240 modification:

RWAK240 Modification: 

2,000uF of super-low ESR power supply rail capacitance is hard-wired directly to the headphone output stages.


With this modification installed, the AK240 delivers the bass weight and scale that is now on par with high-end portable headphone amplifiers.  It extends deeper, hits harder when called upon, and is tighter and more responsive throughout the entire volume range – but is most welcomed at medium to higher listening levels where more instantaneous current is required (especially with lower impedance headphones).  This modification also helps add more depth so certain recordings.

Another area where the stock AK240 headphone outputs can be improved upon is in both the midrange and top-end.  While it does a good job at keeping the sound neutral, the tends to sound a little dry at times – siding towards being more analytical instead of delivering the right amount of richness and musicality that makes you want to listen longer and longer.  While not “hard” or “digital” sounding in its stock form, there is still a certain lack of emotion in the midrange, and lack of naturalness in the top-end that is so important for taking this DAP’s sonic performance to the highest level possible.  After much experimentation, another solution was devoloped with the RWAK240 modification to improve both SE and BAL headphone outputs equally:

RWAK240 Modification: 

Pure Class-A biasing of the headphone input stages via an installed JFET cascaded constant current source (CCCS). The JFET CCCS’s are bench-tested and matched to be better than +/- 0.5% tolerance.


This greatly improves the midrange by making it sound more seductive and natural, and does not harm the transparency and micro detail retrieval of the stock player.  Treble becomes very open, extended and effortless sounding – and these improvements, along with the improvements to the bass response (mentioned above) work together to elevate the stock AK240’s SE and BAL headphone output performance to a level that is competitive with some of the best source + portable amp pairings!


  • Includes the RWAK240 modifications listed above
  • Adds either a SE (3.5mm TRS jack) OR BAL (3.5mm, TRRS jack) true line output jack.  You select the line-out that you prefer.


The line out jack is installed on the angled surface above the volume wheel.  Some machining of the enclosure internally is needed to take place (Very carefully!) to remove aluminum so we can fit the 3.5mm TRS or TRRS jack inside, along with drilling the hole on the angled surface to panel-mount the jack.  This is hard-wired from the output stage of the d/a converters, and completely bypasses the stock headphone output stages and gives you the cleanest possible line-out signal to feed an external portable amplifier.

You will still need to set the volume wheel to MAX in order to get full output voltage (no digital attenuation) from the d/a converters.

Notes regarding the RWAK240 / RWAK240+ modifications

  • All stock functionality does NOT change with the RWAK240 or RWAK240+ ... these are only sonic improvements and not firmware related.
  • Just like the AK100/120 modifications, we warranty the RWAK240 for as long as you own it (applies only for the original owner).  This excludes any issues unrelated to the modification, such as the battery, LCD, etc., but we still try to offer prompt repair service for such non-warranty items.  Price depends on nature of repair.
  • There is an antenna inside the AK player for transmitting WIFI data when WIFI is set to "ON" in the menu settings.   After the modification, we highly recommend that you turn WIFI "OFF," as there is a greater chance that you will pick up high-frequency WIFI noise when you have WIFI turned "ON" (especailly with sensitive IEM's).  Use WIFI for firmware updates, but turn it OFF when playing music with sensitive IEMs to avoid noise pick-up and to maximize battery play time.


RWAK240 (modification only, for AK240)

Pricing for the Modification Service only. Customer must supply AK240 for upgrade. See Terms & Conditions for additional information.

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Price: $495

RWAK240+ (modification only, for AK240)

Pricing for the Modification Service only. Customer must supply AK240 for upgrade. See Terms & Conditions for additional information.

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Price: $795

RWAK240 player

Brand new AK240 unit with RWAK240 modification. See Terms & Conditions for additional information.

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Price: $2995

RWAK240+ player

Brand new AK240 unit with RWAK240+  modification. See Terms & Conditions for additional information.

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Price: $3295