However, if a device passes the J-test with perfect results then one can only conclude that all distortion spuriae including any jitter of any sort are all below the noise floor.
This assumes that the DAC has excellent HF response and transient response. If it doesn't, the spuriae will be masked, filtered.
Take the same source to another DAC that has better HF and transient response and you might see more spuriae. I think it depends on the DAC, which it should not. DAC analog circuits should not be part of the measurement IMO.
Steve N.
Empirical Audio