I have a pair of d-9’s from ‘89 or ‘90 I think. They were loud af, and fun for parties. Seemed to take just about anything I threw at them. The ones you’re looking at will definitely be better than the cubes they’ll replace. I would try and do a package deal from RSL personally, as I think their speakers are overall better than the cv’s, but they will cost more too. Iirc Sony has a speaker comparable to the CV. For two hundred bucks a piece, you probably won’t be blown away, but compared to the cubes, you will absolutely notice a big difference. I wouldn’t feel bad about trying them.