Decouple, if for no other reason that it measures much better. At least with most loudspeakers.
For example soft rubber pads/foam will decouple more than hard ones, but both will decouple hundreds of times better than wood on metal.
Just how far you need to decouple is best judged by listening. One good indication could be how well the bass is playing notes after some decoupling.
It's also quite possible that with some well designed loudspeakers that no decoupling is required. The designer may already have factored in baffle resonance control. Eg Harbeth, Linkwitz, Eclipse TD series, Magico, Wilson etc.
Hence the differing answers.
For example soft rubber pads/foam will decouple more than hard ones, but both will decouple hundreds of times better than wood on metal.
Just how far you need to decouple is best judged by listening. One good indication could be how well the bass is playing notes after some decoupling.
It's also quite possible that with some well designed loudspeakers that no decoupling is required. The designer may already have factored in baffle resonance control. Eg Harbeth, Linkwitz, Eclipse TD series, Magico, Wilson etc.
Hence the differing answers.