Sierra ruined my built in speaker. Everything sounds louder in 10.12. I thought they fixed my Mac mini with this new OS, because it always had a low volume even at maxed. Now my speaker is distorted even if I bring the volume down, which means it has a broken speaker cone inside. I dont know when or how it came to this, I just noticed it today. Back in El Capitan and previous OS, I could hear low volume since its just a mac mini even if I max out the Volume slider. SUCKS!!! So be careful of maxing that volume slider up in SIERRA!