The D500SE has a Crystal 24/192 Chip model CS4391 made by Cirrus Logic. You can read about it at: http://www.cirrus.com/design/products/overview/index.cfm?DivisionID=3&SubdivisionID=8&ProductID=30
1 Bit DACs were commonly called bitstream. They were found on the Cambridge CD4, CD6 and Rotel 930, 950 and 970 all filtered to 20 bit. Do not be put off by the term 1 bit; it is just basically how the chip reads the data before the filtering and/or sampling is applied at whatever rate the chip is designed to operate at.