How do you think a separate DAC will help?
If it sounds good, then there could be other places where you might more benefits.
Do your active speakers have any room correction stuff built in?
Ideas:
I note that my DAC has only XLRs and what looks like a TRS, so one would need an XLR to RCA adapter… or maybe run the XLR to the speakers and the TRS wired to goto the subs.
I would think that XLRs would be better to go direct to you active speakers if they have XLR inputs, and then use the TRS or RCA to go to the subs. That assumes that they are both active at the same time.
And it would be even better if you can apply parametric EQ setting to the TRS/RCA outputs, and then you could do a bit of assistance on the sub to get a better and more even response, independent of what goes to the active speakers.
^That^ sort assumes that you abide a DAC with EQ capability.