The approach you're using- rubber, wood, cones- to ameliorate being on glass is a pretty good one. Glass adds glare and hardness, which you sort of cover up with the rubber and wood, and then try and get some of the speed and detail back with the cones. That's not bad.
Your idea of adding a bigger wood shelf, or entirely replacing the glass with wood, will probably be a little better. No idea what you are looking at cost-wise for that. But pretty sure Nobsound springs will be a lot less money and absolutely certain they will be a much better improvement. Read the threads, these things are absolutely awesome for the money.
But honestly, all these options are baby steps. If you are looking to do something that will be a significant system upgrade, look into Townshend Pods. I would start with a set under the tube amp and take it from there. Not cheap but these are great strides we're talking not baby steps.
Your idea of adding a bigger wood shelf, or entirely replacing the glass with wood, will probably be a little better. No idea what you are looking at cost-wise for that. But pretty sure Nobsound springs will be a lot less money and absolutely certain they will be a much better improvement. Read the threads, these things are absolutely awesome for the money.
But honestly, all these options are baby steps. If you are looking to do something that will be a significant system upgrade, look into Townshend Pods. I would start with a set under the tube amp and take it from there. Not cheap but these are great strides we're talking not baby steps.