And the original magnet was not removed, it just overlapped the new one
Do you have any photo of the n52 magnet on the back of driver?
I have observed this route in other threads in past, and stayed silent, but when it involves this headphones I will give my 2cents, to take is as you will. Because this unit is very rare to be taking similar chances.
So I will clarify my post.
In my experiments on dynamic drivers for years (and have developed my DMT mods as a result), I know that this route has a greater than 90% chance of problems.
The issue is not the potential benifits.
The issue is that this approach is, what amounts to using a gunshot blast, (just to give the motor more strength), when what you really need is precision.
The problem of laying
greater strength magnet on top, is that it does not just increase the whole magnetic field, it
alters it.
The WHOLE magnetic torroidal field is now affected..
It is now
skewed, dependant on size and also it's shape. Neither is less important.
This will, in turn affect its pistonic travel (wether it is linear or not), plus its excursion range, and strength against the acoustic impedance (air resistance in ear chamber).
That is not the real issue I have with this choice of mod, not at all, as that's mostly a sonic choice.
The issue I have, is
longevity...
As time goes on, the permanent magnets interact in a way that will change the torroidal field.
It will slowly be shifted to the center of the magnetic union.
What that means, is that the field will become recessed in.
So what does this mean?
The drivers's voice coil will start to follow the center field, which is further in.
That means when playing music, they will start to "bottom out" and hit the inner excursion extreme, making a crackle sound.
This will not happen overnight. This will happen over span of about 2 months.
The time will depend on both the strength and the proximity of the magnetics, and if they are direct contact, or something in between.
After the permanent magnet of the driver is changed, even removal of the added magnet will not help. It is forever altered, and skewed off center.
So I would ask anyone who performs this type mods, if they also have a solution implemented, to avoid moving the magnetic field.
A proper solution would be Increasing the magnetic field, without a magnetic shift. I don't know of anyone but myself who accomplished this (without changing driver itself).
Driver companies will tell you what the maximum magnet they can do is. They know they simply have limits, as a larger magnet inside would necessitate a longer voice coil, as the center field is further away. so you can't get away from the added mass for added magnetic field with these old designs..
Even Focal with their super magnets have a deeper coil.
Anyways, I digress now, and will just say this long post is just a word of caution.
I hope it works out as a viable solution, and holds. I would hope & assume they already know this.
I do not have this headphones but I did hear them before and Sony did an amazing job in the sound.