There is plenty to suggest there will be a real challenge found to better these Speakers at a given budget.
An Upgrade Route can be extremely beneficial, the Xover can easily be showing signs of age. An investment in this area is a practice that can create a listening experience one could not imagine was possible.
Investing in a selection of the most recognised components for their quality will create a Xover redesign for approx' $400ish. Speakers costing $1M are unlikely to have the components in a Xover the DIY option is able to select.
Amber-Z Copper Foil caps - Mundorf M Resist film resistors along with their heat sinks
http://www.audioreview.com/product/speakers/floorstanding-speakers/von/schweikert-vr-4.html
https://sm5b.se/wp/wp-content/uploads/vr4%20manual.pdf
https://www.whatsbestforum.com/threads/vr-4jr-upgrades%E2%80%A6-also-known-as-mods.35135/