HE5XX Harmonic distortions 1kHz @ approximately 102dbSPL Bass distortion is low. However mid and high distortion, particularly the second harmonic, is a bit higher than what we typically see hovering between 0.1% to 0.5% until the highs which reach 1%. I do wonder if this is responsible for the HE5XX's overall inner warmth. Here is Verum 1 for comparison. Verum has more distortion the mids and less in the highs. and HE4XX. HE4XX has much higher bass distortion. The mids are about a wash. The highs less. I'll run distortion at lower SPLs to see what happens.