The truth is you probably want the normal setup as you will be using the crossover built into the software. The main thing with low DPC vs. normal is that the normal one has the Xonar control center running all the time and that uses more computer resources and adds the smallest of delays. When I had my sub with the H6 I used normal. When I got my new sub with a built in crossover I did not need the H6 and then used Low DPC. Also since you will be using speakers and headphones you will need the control center to switch back and forth so again use normal.
As for connecting the sub, make sure the crossover is set to the maximum as you want the Xonar handling the crossover. As for which input to use, I would say it probably does not matter. I looked at your model and REL is kind of advertising it has having dual inputs and dual volume so with one you can use it for music and one can be used with home theater. In the manual it says to use LFE when you are receiving signal from a processor which is the Xonar so use that. You can always try both and see if there is a difference.
thanks for your reply.
Ok I will install the normal unidriver software. What do you mean by when you said that you do not need the H6 cards sub out no more? You did get a new subwoofer Presonus T10? Does the T10 have more input and outputs than the REL T5?
How are you hooking up your new sub with the STX II or are you using a separate DAC for speaker / sub connection?
Edited by Toube - 2/25/15 at 10:31am