soundsmith can rebuild that dynavector prob alot cheaper than the factory, with a MC cartridge, retipping is often not that far off replacement cost. The cantilever and stylus are a big part of a cartridge's character so it could be changed a bit by 3rd party retip. 200$ for a basic rebuild might be worthwhile however.
https://www.sound-smith.com/options-cantilever-and-stylus-shapes
Music has very little energy in the last octave 20-40hz, except maybe electronica. The chest thumping impact is more like 60-100 hz. Subs give alot of placement flexibility since bass is heavily room dependent and also remove distortion from excessive excursion in the mains.
They really are game changing but you need alot of care and some mesurment to set up right, need some dsp capabilities.
It is basically impossible to get even bass response in a normal sized room with out some form of signal processing, you ears and brain sort of hear through the peaks and nulls however.