Let's get Cooking with some ROMs, straight from Tw6 review kitchen
Intro.
In the last few years Lurker's firmware updates became nearly synonymous with iBasso official releases, adding Google Play (to Android based DX200 and DX150), doing optimizations, and adding some apps. At the same, I noticed here in DX200 thread a discussion about Fidelizer ROMs which got my attention as well. Fidelizer ROM is offered in three versions, a free Purist ROM, Enhanced ROM ($49), and Advanced ROM ($99) which could be upgraded from Enhanced ROM. While I was thinking to try Purist ROM first, I figured it's not going to have all the features enabled to give me a full picture of Advanced ROM sound benefits.
In full transparent disclosure, I didn't buy Advanced ROM, only have their 1.01.006 version sent to me
free for test purpose. If I'm not mistaken, when you buy the full version, you also get their support and lifetime updates aligned with iBasso firmware releases. During my testing I was using DX200Ti w/amp8, but also confirmed the same sound changes with DX200 w/amp1. Furthermore, I was using 64audio U18t and Campfire Audio Solaris for monitoring, and DX200 was set to digital filter 4. My findings are subjective, I just describe what I'm hearing, and I'm not going to be offended if you'll take my impressions with a grain of salt.
iBasso Android Oreo fw1.0:
This is my baseline sound where I took a note of soundstage expansion (width/depth), and sound dynamics (vertical expansion with layering/separation of sounds). Between Mango app (Android OS) and Mango player (Mango OS), I hear a similar soundstage, while in Mango OS the sound is a little more dynamic.
Lurker's add-on update:
In addition to other add-ons (visit the link above for more info), you get Google Play, and improvement in performance, like a more fluid transition between screens in Mango app (Android OS). I find soundstage to be the same, but the sound dynamics has some improvement (Mango app). In Mango player (Mango OS), I hear soundstage just a little bit wider, the rest sounds the same.
Fidelizer Advanced ROM w/PerfectDynamics 2.0 update:
In addition to other add-ons (visit the link above for more info), Google Play is removed (from Lurker's update), Mango app is updated (including visual updates), and I'm hearing a wider soundstage and better dynamics with an improvement in layering and separation between the sounds (more air between the layers). In Mango player (Mango OS), the improvements are the same as in Mango app.
Lurker's add-on update (2nd time):
I went back to install Lurker's add-on update again on top of Fidelizer ROM because I wanted to bring back Google Play. As an add-on, it didn't erase Fidelizer ROM updates. Everything was still there including updated Mango app. Going back and listening again, I didn't notice any changes in technical performance with the sound dynamics still being the same, but the soundstage got a little bit wider in Mango app (Android OS). In Mango player (Mango OS), all the sound changes remained the same (aligned with Mango app in Android OS).
Conclusion.
To make sure I'm hearing all the changes consistently, I did flash iBasso original ROM, Lurker's add-on update, Fidelizer Advanced ROM, and then Lurker's add-on -
3 times in the row, following the same order. iBasso and Fidelizer ROMs take a few minutes to flash, while Lurker's add-on takes about a minute. It's a short enough time where I don't have to go by a distant memory to compare the sound.
The bottom line, I do hear sound improvement, I can't quantify or measure it, it's not night'n'day, but it's noticeable enough for me to appreciate it without wanting to go back. I also noticed that while Fidelizer Advance ROM brings the maximum improvement in vertical dynamics of the sound expansion (feels less compressed, with more air between the layers), the maximum soundstage expansion was achieved after I installed Lurker's add-on the 2nd time after flashing Fidelizer Advanced ROM. So, I would suggest to use both of them, especially if you want Google Play. Btw, nothing is wrong with iBasso original ROM, it sounds good already. These custom ROMs and add-ons just refine the sound and performance, and add some functionality, like Google Play which is a big deal.
Last, but not least, while Fidelizer offers you different ROM versions, from a Free to Paid ones, Lurker's ROMs are free so I hope you'll support him with donations (just my personal opinion, and I know he hates when I bring this up).