Dear Fellow SC IVA owners

Look up Dunlavy SC IV on you tube.
Usually adding spikes or points to the bottom of speakers is for increasing clarity and improving imaging. My SC IVs did not need improvement in these areas.
These are not near field speakers. The drivers are spaced far apart and in order to get a good blend of the drivers there needs to be a certain distance between you and the speakers. This could be the reason for the improvement you heard by spreading the speakers farther apart. These speakers can actually be spread extremely far without any loss of imaging detail.
Dunlavy, one of the best speaker designers in the world, did not believe in spikes. That's why he didn't supply spikes. He didn't believe in bi-wiring either, but he finally gave in and installed bi-wire connectors because reviewers and dealers hounded him to do it. I experimented with bi-wire and single wire. I felt the single wire was more coherent from top to bottom.
Wire used was Dunlavy speaker wire and interconnects.

I absolutely do not recommend adding a subwoofer to the SCIV system. The SCIV is an incredibly coherent speaker system. Adding a subwoofer would only degrade the coherency. Besides, if the system is set up properly the performance from top to bottom is amazing.
Measurements for the SCIV are actually taken at 10 feet not 3 meters.
My best results with the Dunlavy SCIV were achieved by not using an equilateral triangle, but every room is different. The room will dictate the best arrangement.
A true D'Appolito design requires a 3rd order 18bd per octave crossover allowing the drivers to have the same horizontal dispersion characteristics.
The Dunlavy SCIV actually places the tweeter slightly below ear level.
I also spoke with John Dunlavy on numerous occasions along with his marketing manager who's name escapes me at the moment. John recommended starting as close to the wall behind the speakers as possible and moving them out as needed. 44" from the rear wall may be the reason one might feel the need for a subwoofer.
I have the ability to reverse my listening room. I can turn it around 180 degrees. When I set up speakers on one wall the speakers end up about 40" into the room. It doesn't matter what speakers. All speakers sound the best in approximately the same place.
When I reverse the room the speakers can be much closer to the wall behind them because the listening position moves forward. And this is how the Dunlavys sounded the best in my room, close to the rear wall and spaced far apart in a non-equilateral triangle, but this is how my room works and it has nothing to do with other rooms.

Jonathan, I just don't understand how letting your speakers run full range and adding a subwoofer can improve the midrange.

I have heard improvements by using a crossover while adding a subwoofer thereby relieving the main amp of low frequencies and removing bass energy from the main speakers.

What exactly was the improvement you heard? I am curious.