In this paper, we present a design space exploration of optimal many-core processors for the physics-based sound synthesis of guitar by quantitatively evaluating the impact of a sample-per-processing element (SPE) ratio - the amount of sample data directly mapped to each processing element (or varying the number of processing elements for a fixed sample size) on system performance and efficiency using architectural and workload simulation. The effect of the sample to processor ratio is difficult to analyze because it significantly affects both hardware and software design as SPE ratio is varied. Experimental results indicate that a SPE in the range of 2,756 to 11,025 (or the number of PEs between 24 and 96) provides the most efficient operation for synthesizing guitar sounds with 6-note polyphony sampled at 44.1 kHz, yielding the highest task throughput per unit of area or energy. In addition, the synthesized sounds are very similar to the original guitar sounds.