I too am noticing that the midrange and vocals are improving over time. I’m usually too excited to burn in my new headphones haha but yea they sound better than they did at first. I run them on the KZ AZ20 Bluetooth adaptors and they perform fabulously. I don’t ever listen to hard rock but I heard one reviewer use Breathe Again by Pop Evil to test the capabilities of headphones and BOY does that song sound amazing on the Symphony! I’m still curious about the AS24 but for now I’m content with the very capable Symphony.