Subwoofer placement - does it matter?

Positioning is the *most* important thing in locating a sub. Then level matching, then phase adjustment.

Simulators are great for giving you ideas. When I’ve used them, I’ve never had measured response in the room agree with the simulator. Maybe simulators have improved since -- I would expect the REW one to be top of the class -- but don’t rely on them too heavily.

@emergingsoul

If I need to measure it, it seems it can’t be heard.

Is that a question, or have you made up your mind?

You certainly will hear that bass is uneven. How well you can translate that into varying effects at different frequencies, and how they change with position, is difficult to say. Most mere mortals find a graph helps -- a lot! That way, your experiments can be a lot more systematic.

And when adjusting phase, a graph helps a lot. There are makeshift ways to do it without, but you can do it in 30 seconds with a sweep or pink noise and acoustics measuring software.