Have you ever mixed with pink noise for a reference mix/ static mix? From my understanding, the mix Buss should be peaking at 0db when pink noise is audible. And while one is using a sound level meter app, the pink noise should be set between 75db for a small room and 85db for a large room. After that --I take it-- you can raise the volume of each instrument so that you can barely hear it over the pink noise. If I'm missing something with this technique, please feel free to correct me. Thanks, Geddy