okay,
for everybody who got here via google->i found a way to play/upsample to 384khz with this ES9018K2M-Board…
try picoreplayer->audio-options->use “Generic/simple es9023”->advanced->“Audio Card Control”->check “dt-overlay parameters 384k”…
let “onboard soundcard” enabled (had problems with it changing, but try your luck")->check the output with->sudo cat /proc/asound/card1/pcm0p/sub0/hw_params (or …/card0/… if u unchecked onboard sound device)…
additionally change upsample setting to “X” (upsample to max device capacity) and set alsa settings->sample format to 24 (had problems with 32)
so you´re done !!!
(by that: i love Dietpi meanwhile soo much; for me (soundwise) the best audioplatform on a pi so far but with only this “RPI-dac”-overlay compatible with the ES9018K2M)i got 192khz. max and i searched google/dtoverlays for months… 
)
many greets and thx again to the Dietpi-founder (Fourdee) !! 
(PS.: I´ve just have seen that this thread is now first in the list, and so i had an idea: i´ve “extracted” the simple-es9023-audio, simple-bclk-64fs etc…from the “overlay”-folder from the picoreplayer (6 files and newer imo), copied it it into the overlay-folder on the dietpi, changed in the config.txt dtoverlay to “simple-es9023-audio” but in the sound configuration of the dietpi is still the rpi-dac (clear) and unfortunately there is no option to select the “simple-es9023-audio” overlay…also clear, has to be added to the list…found now not the appropriate thread for “extending” the available audio dtoverlays-list…
by that i dont know if thats all that would/should be done or if we need some kernel-patches/or other changes)…
so many greets from here !! )