Sony Mastersound Gold CDs* | Page 8
Of more importance than the gold disc, is the use of "SBM". If I'm recalling this correctly, the analog master tapes are converted to 20-bit digital, and later bit-reduced to 16-bit redbook format by using Sony's Super Bit Mapping process. SBM is apparently very good for noise-shaping when doing a 20-bit to 16-bit transfer.