Crossover with variable slope and time delay

I mention room correction not for the room correction but for the automatic subwoofer configuration.  Without some experience and tools this is not trivial and ARC systems can do this exactly right every time.

NO worries. I just wanted to understand just how much flexibility you needed and whether you had the tools and experience to set them accurately.  Otherwise, a system with built in room calibration is a lot more suitable.

You can use almost any of the miniDSP units for your needs.

Lets back up a bit.  Why do you need this?  What is your goal and how are you thinking you might achieve this?

Otherwise, you can always use a miniDSP unit between your pre and amp for this.