The Octopre ADC specs are:

0dBFs = +22dBu
S/N = -109dBfs measured with A weighting filter at 48Khz sample frequency.
THD = <0.003% at 0dBfs with 1KHz signal measured with 20Hz/22Khz band pass filter.
A/D Clock Jitter = 200 pico seconds measured using 700Hz to 100kHz bandpass filter.
External wordclock jitter = <2 nano seconds measured using 700Hz to 100kHz bandpass filter.