You always change the region code with the
Rockbox tool and see how it sounds then. Regions J & MX3 are frequently recommended on the WM1A forum, my own ZX-300 is flipped from region E to J
CN - Tuned for the Chinese market, heavy on resolution, bass is tamed
CA - Mid bass spills over, big fun & bouncy wears off in time
J - Relatively neutral, little veiled in the treble, equally allows for prolonged listening without fatigue
E - V shaped, can be piercing with some highly resolving IEM's, fine on ZX300, not so much on WM1A as is more resolving
MX3 - U shaped very musical and enjoyable
TW - Trades off resolution for bass, with narrower staging
There are 16 regions in total, the changes are nuanced, depending on your IEM & HP, choice of genres and hearing the difference should be apparent; if I had to call it
J &
MX3...
Avoid the EU regions as they are volume limited (CEW & CEW2)
Q-6