Generally speaking, the power rating of the speaker does not determine the break-up mode. Break-up is most influenced by the cone. It commonly occurs quicker in thinner, lighter weight cones. However, higher power speakers often have heavier cones with slower break up, but not always. This is why we have a column on our Guitar Speaker Tonal Characteristics and Application Guide for break-up modes. With that guide, you can compare how the speakers break-up in relationship to one another (slow, medium, fast).