As far as I remember reading, the 598 decodes DD and DTS and converts it to multichannel PCM 24 bit. The 568.2mm via smartlink only then takes each channel and upsamples it from 48k to 96k. 2 channel PCM input only via SPDIF is also upsampled in all channels in the 568.2. DD and DTS via SPDIF is not converted to 24bit, 96k in the 568.2. I find the difference quite noticable. Upsampled movie sound is noticably better. More dynamic, smoother and more natural sounding. More depth of image. Especially DTS upsampled. WOW!.
You tease, you. I wish to be woken when pigs start flying and we can enjoy such delights on a 568.2 with the new next-gen codecs thanks to a magical HDMI to MHR box of tricks that Meridian are bound to never invent.