Don't take this to mean the three π is distorted though. It is a very nice speaker, and you don't really notice the distortion even at high volume levels. The only way to tell is when you A/B them, you can hear the four π being clearer.

The other thing I notice is long duration listening fatigue. The three π's never really sound distorted, but after a couple hours at high volume, you want to turn them down. This isn't so with the four π's. In fact, it is probably something you should be careful of because listening fatigue doesn't set in for days. Seems like you can play them very loud forever, because even after several hours you still feel refreshed and don't feel the need to turn down the volume.