Here's a opinion by me.. Something I found out to be better.. Worth the try
For all Sony Walkman including those ZX or A series here.. I tried it all.. All stock Walkman with Equalizer turned off sound like the 60hz boosted, 400hz lowered, 2.5khz boosted, 6.3khz boosted
Turning off Equalizer makes music sound thin and piercing. Vocal sound very bad.
The solution I accidentally found was...
Turn off all other built in enhancements like DSEE and DC Phase Linearizer except Equalizer
TURN ON EQUALIZER BUT SET ALL VALUE TO ZERO!
Try it.. You'll notice the bass is not so bloated as before , low mid 400hz become better.. Thicker body Vocal.. The 2.5khz frequency sharpness hiss disappeared too, or else the word T or S sound like a sharpened edge knives sisss... Pain and piercing.
In the end the music sounded more natural and flat and accurate!
Is just my opinion , but you can try and see if you liked it
The gears I used to test
Walkman A45 Vol 97 + Fiio L16 cable to Fiio A3 High Gain Vol <5 + Audio Technica M40x
I have been living with the A45, and have always abhored the sound signature until I found out about this! Thank you for this!
Now I quite appreciate the A45 with the 0EQ feature; added body, less thumpy, and no more of that piercing, thin upper range! What a treat!