My dad has a pair of late 1970s ('78 iirc?) Technics SB LX5 3-way floor standers. Despite their age, they still sound pretty good, but i dont have too much experience with Hi-Fi, but Id say "rich" and "warm" are pretty good descriptors, esp when compared to my personal Samson Active studio monitors with a 5" Woofer and a folded ribbon tweeter. There are no issues with the cones, domes or the surrounds, thankfully, but its definitely not without its faults, cuz it looks like it was made with rather cheap particle board, with no infill or possibly even bracing.
But I was curious if it would be worth doing some internal upgrades?
For example, upgrading the crossover with the same but newer, better quality components/wiring, and installing some braces and NoRez, along with tube connectors instead of clamps, to keep the original looks, but increase their clarity & reduce its cabinet resonance?
Or is this just a case of "If it ain't broke, dont fix it"?