New MrWalkman firware is out for the Sony NW-A55 (and other variants).
However, there's a surprise: it's the firmware that basically mimics the sound signature of the Sony WM1A/WM1Z. You can download it from the following link:
https://www.mrwalkman.ml/p/midnight-v2-for-a50.html
I installed it asap and took it for a quick test. There are indeed eerie similarities to the Sony WM1A (when modded with MrWalkman Midnight firmware). In fact, right now this new firmware is my most favorite firmware for the Sony NW-A55. The staging is the best among all MrWalkman firmwares till date, and the sound has slightly smoothed out transients, resulting in a very pleasant sound signature.
There are differences with the actual WM1A though. The WM1A has better driving power and dynamics, and most importantly resolution/imaging is superior on the WM1A. Other than that, it's kinda similar between them.
So you're getting the sound signature and about 70% performance of a $1500 DAP in a $200 DAP via a simple firmware upgrade. Not bad, not bad at all.