As a newbie, I have done a little research on external component-style DAC's and have found out that there is a newer kind rated at 24-bit at 196, 192 and 384 Khz and an older kind rated at 16-bit (unknown what the Khz resolution was). Are there any other bit-rated kinds of DAC's beside these two such as an 8-bit DAC? Why the jump from 16 to 24-bit, shouldn't it have jumped to 32-bit instead, going by conventional computer bit leap-frogging sequencing? In other words shouldn't it have doubled in bit rating? When did external component-style DAC's first come on the market anyway?
 
Thank you

Read away:
 
http://en.wikipedia.org/wiki/Audio_bit_depth