Older electric guitars use nitro lacquer, but older acoustics use shellac. I did a French polish (shellac and alcohol rubbed in with olive oil as the lubricant) on one of my Tele style guitars. Is it better than the Tele I finished with nitro lacquer? Impossible to say - different body wood, different fretboard wood, different pickups - so many variables make them sound very different. It does make the neck feel really nice, not as grabby as lacquer.
My take on this is the damping affect of a plastic finish should be an advantage for an audiophile speaker cabinet. Enhancing cabinet panel resonances is not the way to create a coherent sounding hi fi speaker. Might be worth playing with on guitar amp cabs though. Funny that those are often the cabinets that get all the rubbery contact cement holding down the lossy vinyl or Tolex cover on them. Tolex might be a very interesting finish for a hi fi cabinet. The carpeted PA speaker kinda makes sense too.
I think the perfect hi fi cabinet might be 2" thick aluminum covered with 4" thick wool felt and a silk stocking...
