@milpai - Great question.
One of the reviews on the Gryphon 120 was done by the amiable “Pursuit of Perfect Systems” English reviewer. He references the dark quality of the treble in the review, below. I feel his review is absolutely spot on, by the way.
https://www.pursuitperfectsystem.com/entry-level-gryphon-the-diablo-120-integrated-amplifier-review/
But what exactly is that dark quality mean in my experience?
When I connected the amp to my QLN prestige 3 speakers, which are incredibly balanced and relaxed, the treble sounded like it went down an octave. The highs were muted and the treble energy was diminished. The air on the high frequencies was muted and recessed. I was somewhat disappointed because the QLN speakers have been my reference speakers.
Due to circumstances, I had a pair of Dynaudio Heritage Speakers in the house that I wasn’t using as frequently. Why? Because I felt they were a little tipped up on the treble compared to the QLN speakers. But when I moved the Dynaudio Heritage into position with the Gryphon 120, the synergy was immediately evident.
I will back off from my soapbox now. Just sharing my experience and enthusiasm for the amp when you pair it with a complementary speaker.

