Excellent! I'm a keyboardist and used it as a stage return. I like basshead, no shrill high notes. I have used ZSN Pro, KZ ESX, ZS10Pro X, Moondrop Chu II, 7Hz Zero 2, and KZ ZAR. I was satisfied with the zoom; going from it to zero red was like having low-level myopia and not realizing it. The vision was corrected: I noticed more details and richness, without harshness in the highs and with exciting lows. The resonance in the pianos is very good, with high-pitched textures that are not shrill. Playing with the band, without EQ, in moments when the guitar and keyboard were full, they seemed a bit subdued; however, voices, guitar, and bass were always present, in moderation. Turn the guitar up high to analyze distortion and harmonics: no issues in the treble, no discomfort. NOTE: A reference song with arrangements that I can only hear clearly with the Sennheiser HD599; on the Zero Red I hear better than with other in-ear headphones, but not as well as with the HD.
