Electronic – High Quality Audio ADC and DAC with Embedded

It would depend on the parts you're using. ADCs and DACs are more likely than not going to be slaves that would expect some controller to give them a clock signal.

If you want to test a preamp, could you just use a signal generator in place of the DAC output? That, or design in whatever DSP you want to use and write some quick code that simply passes values through.

In all likelihood, the ADC will: -

1. Sample the signal
2. Convert the signal
3. Feed out the digital representation of the signal
4. Repeat

This means the latency is approximately the time between consecutive samples. More sophisticated ADCs could be (or can be) sampling the input signal whilst feeding out the digital value of the previous sample but, given that sampling is usually quite short I'd say you can use the inter-sampling time as the latency.