Then, according to this statement, you can conclude that the Wilsons can "never" be correct. Since the speakers are always connected to the subs and according to you, they shouldn’t be.

@gdaddy1 No, and as with most things in audio it’s a compromise. While the designer gets to implement the crossover and there are some advantages of things like potentially better impulse response, it comes at the high price of having to design/build much heavier/more expensive cabinets and placing bass where it’s not optimal and most likely creates significant bass problems in a room. And in this particular case, which is what we’re really talking about here, where the OP already has subs it would be both silly and counterproductive to place them where they most likely will not sound best and cause room-induced bass issues. Plus, putting a speaker on a big, vibrating beast if not necessary is just a stupid idea — vibrations negatively affect sound, so adding significantly more vibrations into the speaker is just never a good idea, period. And on top of that and as someone else mentioned, it’s also likely the speakers will not be at the proper height plopped on top of a subwoofer, so for all these reasons it’s just an awful idea to put those excellent and expensive speakers on subwoofers.

@gdaddy1 First of all, those Wilson's are incapable of projecting 20 Hz into a closet. Frequency response specs are extremely misleading being taken at one meter. In short, they are not subwoofers which for the majority are poorly designed, cheaply manufactured and vibrate like crazy producing vast amounts of distortion. 

Having said all that there is absolutely nothing wrong with placing a speaker on top of a subwoofer as long as nothing rattles. Isolation feet are for the most part a joke. I would put some self adhesive felt feet under the speaker so that both surfaces are protected from abrasion. Make sure the subwoofer is dead horizontal or the speaker might walk off with the vibration.   

We can take the “height” issue off the table.  The Tontregers place the tweeter too low for my application.  The optimal height to raise the 40.3 is pretty close to the height of the sub. 

@soix 

vibrations negatively affect sound, so adding significantly more vibrations into the speaker is just never a good idea, period.

Agreed, but that's NOT what I'm suggesting. I want to eliminate all vibration going to the speaker and it's absolutely possible. I agree that the tweeter height must be within range of your ear height. If it's too low the speaker can be adjusted higher using stands. The only problem would be if they are too high. You are assuming this mismatched condition is "Likely" when it hasn't been measured and we don't know.

@mijostyn   

Isolation feet are for the most part a joke. 

Believe it or not there is big difference in the dampening affect from different materials used in vibration control. It's not a joke, it's science.

Don't Set Your Subwoofer In The Corner see here!

Mike