Control volume with DAC or Preamp?


My DAC (PS Audio Directstream) has a volume control and so does my preamp(Benchmark), of course.  What’s the best way to control the volume of my system to get optimum sound...turn the dac to maximum volume and use the preamp to make adjustments , turn the preamp to maximum and use the DAC for adjustments, turn each of them up part way? Or does it not make a difference?
wolverine1
Ralph is product (his active preamp) protection mode, omitting the reason behind a "why" the "rare" times a passive "may not" be the least coloured, least distorted, and best dynamically
The reason passive controls tend to sound more colored is they are unable to buffer the control, they are unable to control the otherwise audible artifacts of the interconnect cables. They sound best (more bass, more 'realness' across the audio band) when the control is set to maximum but of course this isn't practical. 
@atmasphere, I’m not sure that one could accurately describe the OP’s direct from DAC to amp application as “passive”?
Only if the DAC has an a proper analog line pre stage. Volume control via DAC chip is to be avoided period. In generally a high quality separate pre will always be better.
The OP's is not passive you are right but in the thread above you will see GeorgeHifi comments about " Ralph is product (his active preamp) " etc. and for some reason (and I have nothing against GeorgeHifi) he has some feud with Ralph, he even quotes Ralph's phrases " This statement is false," so the thread deviated into this arena ...
@madavid, why should ...”Volume control via DAC chip is to be avoided period.”...?