In composition and arrangement using existing DAWs, users set appropriate timbres for each track from vast timbral datasets classified by category (such as instruments and sound source names). We reconsider this current text-based timbral search interaction itself and propose a new approach to expand creativity across diverse timbres. We have removed the conventional concept of timbral categories and have: 1) calculated relationships between timbres depending only on acoustic features, and 2) constructed an interface that enables visual confirmation of relationships between timbres. By visualizing similarity between timbres across categories, we provide serendipitous timbral exploration not constrained by conventional timbral categories. In this presentation, we will discuss the background of the proposed approach, technical overview, and usefulness based on user testing.