The wood of the spruce tree (Picea spp.) has been valued for centuries as an ideal soundboard for stringed instruments due to its material acoustic properties. There is large variability in these properties between individual trees of the same species and even within an individual log. It stands to reason that this variability would produce audible differences in the sound quality of otherwise identical musical instruments. Furthermore, there may be a suite of physical characteristics of the soundboard that would result in optimal sound quality for a given design. Nine steel-string guitars of the same model were produced. The guitars varied only in two parameters: the density and Young's modulus of the soundboard and bracewood. This variability was representative of the range of wood currently produced by Pacific Rim Tonewoods. A short music sequence was used for a pairwise preference evaluation in a listening test. The results suggested that, for this particular model (the Taylor 814ce Grand Auditorium), the low density and Young's modulus of the soundboard and bracewood had a positive impact on the sound quality. More generally, these results underscore the importance of integrating a given design with the physical characteristics of the component wood.