Word clocks are actually not applicable to many modern DAC chips. If you read the datasheets, it is the Bit Clock or BCLK,SCLK that actually does the final clocking through the DAC chip in many cases. If you implement a word clock on one of these chips, it will have virtually no effect on jitter. Examples are:
AD1853, PCM1704, possibly AKM4395, CS4397
WM8740 uses the word clock, but can even resynchronize this depending on the phase between L/RCLK and SCLK.
I think a lot of designers are still under the impression that the word clock actually does the final clocking in most DAC chips, when it is not the case. Depends on the DAC chip.
Steve N.
Empirical Audio