You're generalizing from an inappropriate instance, Hendrix.
The violin - any violin, not just a Strad - is a completely different instrument from an electric guitar, and the mechanism whereby its sound is amplified is completely different as well. The violin's sound comes from the vibration of a string under tension, and the sympathetic vibration of the top of the instrument. Likewise with acoustic guitars. The sound is focused by the sound holes and/or the carved profile of the top; and the volume is also affected by these. The electric guitar's sound comes from the string under tension vibrating within the field of a magnet, which generates an electrical signal that is amplified and emitted through a loudspeaker.
Further, if scientists have been unable to replicate the Stradivarius magic, how can one categorically state that the magic is in the varnish and the neck-to-body joint? There have been all manner of studies done on the provenance of the wood he and his apprentices used, the varnishes, carving and joinery techniques, etc., etc., etc. - and while theories abound, I am unaware of anyone having pinned the problem down so concisely.
But I'm pissing in the wind here, since it's not clear you have a real question in the first place.