Before focusing on details commonly known by most makers and musicians, I would like to catch your attention on an apparently insignificant part of the sound of your instrument: the upper nut.
This detail should be taken in consideration seriously, since it is one of the two starting blocks for your best vibrating string.
Try to consider that your hypothetical supersounding instrument sounds because of a vibrating string. Exactly that string is kept from one side to another. And the upper nut immediately turns out to become obviously a soundeffecting part of it.
I imagine that the sound is transmitted somehow like temperature from one part to another. Therefore it is very important that every single string lies with a good distributed preassure on the upper nut.
Watch my video about the Upper Nut: