Easiest:
Run full range to mains. Run line level to sub EQ, use sub EQ to integrate.
Cons: You don’t get increased output from your main amp. No extra dynamic range. Sometimes a compromise is to plug ported mains.
Highest dynamic range, most altering of main signal:
Use a crossover after your preamp, before your main speakers.
Cons: Adds more processing steps in series with your fancy DAC/pre and amp.
Pick one.
Run full range to mains. Run line level to sub EQ, use sub EQ to integrate.
Cons: You don’t get increased output from your main amp. No extra dynamic range. Sometimes a compromise is to plug ported mains.
Highest dynamic range, most altering of main signal:
Use a crossover after your preamp, before your main speakers.
Cons: Adds more processing steps in series with your fancy DAC/pre and amp.
Pick one.