Control volume with DAC or Preamp?

Listen, is best advise. But full throttle on anything, may not be the best Idea.. My server and SACD, both have volume control. I set the volume at 60-80%. I get pretty good SQ there and a little pre and source  headroom.

Just for the heck of it, does the manual address the issue?

Regards

I'm not sure on that exact DAC but generally think you want to run the DAC in "DAC only" mode which skips the DAC volume control and puts the full DAC output (balanced or unbalanced) into the pre-amp. Then use the pre-amp for the volume control. 

However, there are some pretty sweet combined DAC and pre-amps but assuming this is more of a headphone amp type setup?

With that said it is fairly easy to try it both way and listen for yourself. I have a simple topping DX3pro as my DAC and used it a as pre amp temporarily with mediocre. But it was not built to be a real hifi pre-amp but a headphone amp so knew this was far from ideal. 

You have a really nice preamp that adds no noise or distortion to the music path.  I would go with using the Benchmark pre for volume control.  You should then turn the dac volume to 100% so you get the full signal going to the pre.  The way it was explained to me is you want to push a full signal to the last car in the train before attenuation.

When I inserted the Benchmark pre into  my system, I  noticed immediately better sound at lower volumes and much much better and granular volume control than the dac.  You may have to adjust the pads at the XLR outlets to properly match your components but that is better explained in the user manual of the Benchmark.

The most important thing here is that typically and I personally don't know about the Directstream Dac but most dacs do it, you set the Dac at full volume, you will most likely bypass any DSP stage, DSD to Pcm internal conversions, and possibly even filters leaving the source mostly untouched, if your preamp is good I think that would be the best way to go

I have a Berkley Alpha in my small system (with preamp) and Berkley says set their dac to 51 (volume) when using a preamp.  There should be an optimal setting on the dac and you should control the volume with the preamp.  Volume control on the dac is tough to get right.  Listen to what happens to the midrange as you increase & decrease volume digitally.