Shown at the Heathrow HiFi Show in London over the weekend of September 19th/20th 1998 was a possible replacement for Compact Disc from SONY. Called SA-CD (Super Audio CD) it promises higher-fi than conventional CD by using a technology known as DSD - Direct Stream Digital.
DSD gives multi channel digital sound, over 120dB dynamic range and a frequency response up to several MegaHertz. In layman's terms it's 'Super Fi'
It also promises compatibility with existing CD by using a 2-layer 'hybrid' disc. One layer for SA-Cd and one layer for 16-bit PCM - as used on regular CDs