Check out the speak.ino in the new M5Unified library v0.0.5 it will compile with the Core2 or the Tough and produce sound. There is a M5 speaker class , that can be used to produce tones. The problem is that while the library works by itself it is Not compatible with M5Tough.h or M5Core2.h files. And yes , there is a problem with the Core2 and Tough speak.ino the Log file shows a conflict with mclk pin config , when trying to setup the I2S sound The error is in a higher level M5 system file that was introduced when the Tough was released in the Fall. Sorry , I dont know how to fix it.. -Brent