Well as I have stated before I was no stranger to enjoying Whitigirs mods; The hugely successful AMP8EX for the previous amp architecture of ibasso DAPs (160,200,220,240).
Simply I couldn't wait for what he was cooking up for the the AMP12 so after an enthusiastic inquiry I got an early recepie blueprint of swapping and soldering about 10 capacitators and thus creating what is now known as AMP12W.
But it seems Whitigir felt like the AMP12 could be tweaked further still, so after extensive time spent testing the very limits of the Amp12 , Whitigir crafted yet another recipe. Tweaking and tuning with, in just his estimate, 30 or more components the result was something he felt was now worthy and deserving of having the EX (extreme) suffix.
-Crafting the AMP12 EX was an effort he called "the most extreme of any modifications by far".
When I heard it was finally done, having enjoyed the AMP12W greatly I was eager to hear the EX.
What follows are my impressions using Whitigirs personal made and used AMP12EX board (so fully burned in) inside the DX300 of course and paired with with MMR Thummim and PW Audio Metropolis 50.
Having the first few seconds of my test track played , (volume set as I would have it on 12W) instantly noticeable was the vastness and airyness of the soundstage.
The sound went from perceiving to listening a band performing inside a studio to a band performing inside a much wider studio that had no ceiling on top.
Just the sheer openness of the sound put the first smile on my face.
Treble performance, In comparison to 12W , took my attention immediately afterwards.
It became lusher, more laid back, sweeter, presenting even more details but with less aggression in doing so.
But mainly, as I will point out later also, it was quick!
Just spawning fast and with stunning ability to layer sound up on top in the added space.
Vocal presence got a boost but stayed in the same position as they have in AMP12 and W.
The mids on the whole were a touch more fluid, notch more detailed and a bit more tube sounding.
I found the 12W to exhibit glare especially in some female vocal rendering. This was not the case anymore with the EX.
This, I think, also makes the EX more pleasant in dealing with digital harshness - hence I could say also it is more analogue sounding.
Bass got pulled back a level in terms of presence but got a more solid layer in texture and tightness.
Amp12W presented the bass with more weight and slam while the EX does away with more speed and impact.
In terms of timbre the sound is closer to natural/organic then 12W which had a more boosted and "amplified" feel to it. On the whole the EX has less sound density compering with W - probably aiding and enabling it further to feel more open and fast.
Technicalities wise it is an improvement in details by a notch and handles imaging with firmer precision having also better depth* (*hard to asses quantitatively as I use just iems)
AMP12W felt like a muscled up AMP12.
Like a juiced up athlete looking at what the competitor (amp12) is doing and doing the same just better.
Having much of the same qualities as it, just having them amplified across the board.
But the AMP12 EX feels like a different amp almost entirely.
Different sound aspects got, not boosted but presented in a different manner; be it by different timbre , texture, presence etc...
To follow up on the, hopefully sense-making, athlete analogy, the EX is performing with a different game plan, utilising more agility timing and speed rather then power and force to ultimately over achieve the 12W at least in the game of audiophile fidelity.
I would love to take the closing words here to thank and show appreciation to @Whitigir for continuation of his work in creating these mods for us.
They are an exciting way for us to enjoy our gear and our music and make the very most out of the hardware we pay for.
The AMP12EX is a stellar effort that left me in amazement more so than AMP8EX or 12W.
I wholeheartedly root for @Paul - iBasso and the team to try and work with Whitigir and making this a production run like the FE edition of the 8EX.
Therefore enabling the broader sum of DX300 owners to enjoy the performance of their DAP to a significantly higher point !