Sao relief? Truss Rod Relevance

I had read or saw in a video somewhere that Kyle was in the process of making a shamisen with a truss rod. Is sao/neck relief really an issue with shamisen? I was fortunate to be trained in guitar setup by some very experienced techs and while I can totally see the benefit (and have made use of) the truss rod in a steel string guitar to adjust relief, I’m not sure I see the benefit in a shamisen.

Specifically, the string tension on a shamisen is so low. I’d venture to say that even my ukulele’s have more string tension. It’s been drilled into my head that you never effect the truss rod to inform action but rather to compensate for relief changes in the neck, so I have to think the purpose of the truss rod would be the same for the shamisen (particularly since action can so easily be changed simply by changing the koma).

Am I missing something here?

Am I missing something here?

Indeed… not I think! I believe Kyle said the theory was that it might improve the tone or resonant quality, which sounds a bit far fetched to me. Moreover, so far I’ve not seen him in any hurry to make one with a truss rod.

Well, I can see it being useful for single-piece sao particularly a thinner neck model which might be subject to some bowing not from string tension but from simple environmental humidity changes.

I’m very new to shamisen so I’d defer to Kyle on the subject matter, but I’m not sure I understand how a truss rod improves the sound at all.