Just an update, treble is great now, open and airy and the RE-600s just sound so expansive. I still need to EQ the HM-700 though. For Doom metal it just lacks a lot density in the hi and lo bass. The really deep bass comes through well but the guitars just sound too trebly and really lack authority. I think an EQ tweak should thicken things up nicely though. EDIT: Yep EQ boost worked wonderfully. This combo continues to impress me!