I appreciate the intent of being fair, however 2V into an HD650 is 108.5 dBSPL and 4V is 114.4 dBSPL. Those are VERY LOUD levels. Transducer distortion will rise significantly, especially at low frequencies, certainly masking any amplifier distortion. ASR is plain FOS on this account. Denigrating amplifiers for distortion when clearly it is transducer distortion dominating audibility is a big detraction from credibility.