Should speakers be upgraded before preamp and amplifiers?

I just read that some people use sand instead of lead shot in the V-2's.

This would be less hassle and quite a bit cheaper.

Just us bone dry sand as sold for sand blasting.

If you get silica sand try to load them outside and wear a decent mask as the dust from it is not good for you (once contained it's not a problem).

I have silica sand in my Target speakers stands and filled them that way.

Google - Von Schweikert VR-2 lead sand - and you will get lot's of info.

Recall reading an interview with the designer about the fill years ago, but did not come across it when searching today.

DeKay 

Speakers only reproduce what they are fed

With your budget and goal of adding a tube preamp, start with upgrading to a quality tube preamp and a solid power amp (e.g., Audio Research, PrimaLuna, or McIntosh). Your VR-2s are good, but upgrading speakers like Vandersteen or Harbeth could bring a major improvement. A modern turntable (e.g., Technics SL-1200G or Rega P8) with a quality cartridge and phono stage would refine your vinyl experience. Don’t overlook room treatment and power conditioning for an extra level of refinement