Should speakers be upgraded before preamp and amplifiers?

If possible, listen to different systems to define the sonic and physical attributes that work for you. Then narrow your search to components within your budget that have those attributes. You'll have your road map. I would go after the sources and el electronics. Then the speakers and the room will be the limiting factors. 

@daveoman 

We addressed speakers and amps, but after they’re sorted out, your turntable might be a sonic bottleneck. So agree with @dekay that an upgrading to a reasonably priced phono stage a great idea. 

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