as per
@Whitigir request I converted some of my files (both 16/44 and 24/88) to DSD256 using xivero as test mode.
This is what i heard and i think the WM1x walkmans are already too good at decoding PCM in 16-bit and 24-bit. I heard the DSD256 had less resolution than the originals untouched, even for 24-bit FLAC these sounded fuller than their DSD-up conversion counterpart.
The DSD upconversions lost resolution through the frequency range (from bass to highs), you could note for example bass having less bite and slam power in the DSD256 upconverts, some high and mids frequencies details easily noticiable as less prominent or gone. However there is a thing that struck me. In contrast to Weiss engineering Saracon tool which made the resulting PCM sound darker and less refined. The xivero made the resulting DSFs sound brighter and sometimes out of tune! and less refined or with some artifacts like warbling, "birdies", mettalic whine.
AT times with certain files there was no difference at all mostly organ or orchestral. But hell listening to a Monteverdi madrigal from his Ottavo libro dei Madrigali, made inmediately noticeable, the prominent Bass man singing had less prominence and sounded dull on the DSD256, switching to the original 16/44 his deep voice rumbled and hit deep low.
so A) WM1 walkmans are already too good at decoding signals that you get the minimum amount of imperfections listeneable during playback.
B) perhaps DSD512 is different or C) his iBasso DX200 (priced about the same as my WM1A) is either fooling him with a DSP or it is not as good as the Walkman.