This technology is new - only a few months old. Its a file-based upsampling to high sample rate PCM with near perfect signal reconstruction using hundreds of millions of taps. Your FLAC or DSD get remastered to 8Fs-32Fs PCM WAV files. Main site is here.
Certain DACs can take up to 32fs sample rate PCM (at 32bits/sample) for tremendous SQ benefit. PSAudio DS tops out at 384kHz PCM (8fs) but it still sounds very very good. For anyone with a reasonably powerful Mac or Windows box with more than 16Gb, you can audition use the desktop trial mode. There is also an online version.
Audiophile Style has the main thread for those wanting user feedback: