I love the PEQ, use it to EQ the HD650 closer to a harman curve. It's a great EQ. Jotunheim and ADI's head-amp are different. I can't make one sound like the other with only EQ. I do know the ADI-2's got 6 OP-amp's in it's headphone output circuit, 3 per channel. I don't think the RCA or XLR output's go though this circuit. So from what I gather, you have in fact not heard the THX 789 paired with this dac. Too bad, really wanted your honest impression. Wasn't trying to start a theory craft debate here, only offering my actual listening impressions with gear that I own. If you don't appreciate the small nuances your in the wrong hobby, and the wrong forum.