Native DSD makes DSD 512 version of the Sound Liaison DXD original, upsampling???

[christian u]

Help me understand this;
Native DSD has just released a sampler with 5 tracks in DSD 512.
It says; "These higher bit rate DSD 512 tracks are all pure DSD created. They are not up samplings, for there are no PCM or DXD conversions involved in their production."... ?
I happen to own the last track of the sampler, the sublime live recording of The Feenbrothers playing Brubeck,
and I know that the original recording has been done in DXD 352. That's what it says on the https://www.soundliaison.com/ site where the DXD version is still on special offer.
But how can it not be an upsampling? Or is it OK because DSD is a different format from DXD?

https://www.soundliaison.com/index.php/453-new-the-feen-brothers-one-mic-recording

https://nativedsdpresents.nativedsd.com/albums/NDSD013-nativedsd-presents-5-tracks-in-dsd-512

 

[christian u]

Native DSD says "These higher bit rate DSD 512 tracks are all pure DSD created. They are not up samplings, for there are no PCM or DXD conversions involved in their production. They are re-modulations of the original DSD 256 encoding modulation that produced the DSD 256 releases. The sonic advantage to these new Stereo DSD 512 releases, as with all higher DSD bit rate releases, is the wider frequency passband prior to the onset of modulation noise. This results in the listener’s DAC using gentler and more phase linear filters for playback of the music."