Try the signal straight from the source to the energizer to rule them out and listen again and get back, very interested.
just the hd600 and the koss.
And tell us the good and bad points of both for sound.
resolution, detail, soundstage, instrument placement, treble, mids, bass, or lack thereof, dynamics and slam, vocals, female and male, drums, guitars, and strings, and overall comfort.
Thanks means a lot.
As this headphone has comments that...