I have two SVS subs.
The PB2000 pro is in the basement listening room/mancave. currently that one is is volume -18 db, and low pass is generally kept at 50hz. Depending on the music will adjust. It's paired with stand mounts with (supposed) extension to 45hz.
Upstairs I have the 3000 Micro. As the room is a bit more lively my volume is -22db and low pass is at 40hz. It's paired with larger floor standing horn loaded.
Some of this depends also on where the sub is placed in the (my) room. In the first system, it's a bit more out in the room, away from walls. The second, needs to be a little more hidden, therefore closer to the back and side wall.
One of the coolest things about the SVS subs is the flexibility with the phone app. Play around with the app and placement of the sub in your room. Have fun with it. Trust your ears, you will find what sounds best to you.