CD's/SCAD/HDCD-signal out

As I get further and further down the digital path I think that I am missing the basics to better understand the total system.

So can some one help me understand the ins and out of the digital out

First I would like to know what are the differences in the signal out of the three different disc formats.

Standard CD has what Bits/frequency
SCAD has Bits/frequency
HDCD has Bits/frequency

Out put on DAC's
Standard USB is 16/44.1 or 24/44.1 incorrect or correct
Toslink what is normal here
COAX again what is normal

And other than the bits and frequency what is the advantage of each

Thank you in advance
Format 16 bit PCM
Sampling frequency 44.1 kHz
Dynamic range 96 dB

Format 1 bit DSD
Sampling frequency 2822.4 kHz
Dynamic range 120 dB

HDCD is a compressed format encoded on a regular cd with the same sampling rate only that the depth is 20 bits instead of 16. you need a HDCD decoder in the player to play HDCD's

SACD's use a layered CD/DVD combination that can be read on both a regular cd players and SACD player, there are other combination's where a SACD can only be read by SACD players.

Perfect reconstruction of a signal is only possible when the sampling frequency is greater than twice the maximum frequency of the signal being sampled so a CD can produce a frequency range of 20 Hz to 20kHz and a SACD (played on a SACD player) can produce a range of 20 Hz – 50 kHz. anything above can not be encoded without distortions that exponentially increase as you go above the range.

S/PDIF Toslink Optical orCoax are essentially the same signal and are theoretically capable of carrying data at 125 Mbit/s

When connected to a CD player the data is sent uncompressed at 48 or 96Khz, compressed data for formats like Dolby/DTS can send much more information across.

Hope it helps.