Long term break in effect?
This is a frequency response graph using the EARS platform (Pixel 2XL, apple USBC DAC now/Google DAC initially) of when I first received them and yesterday. The bass response is enhanced after time, but it could of course been positional/seal change as well. For those of you who note peaking in the mid-high region, that 4Khz spike is very consistent and is there every time I've tested. I personally cut it down about 5dB via equalization.
Blue is now
Red is initial (9/25)
Similar graph and compensation curve on some other planars I have -- super busy chart. sorry.
Red: Unique Melody ME1 Planar IEM as a Universal IEM. I converted this shell to custom IEM recently and it changed the sound quite a bit and I think its quite close to neutral now, maybe a tad south of it in the upper mids.
Blue: Hifiman HE560
Green: Audeze Mobius
Black: Audeze Sine - not the seal on these is challenging with ears since the pads are on-ear and are shallow and small.