Listened more using a pair of my son's Sony 7506. Be advised I usually listen to speakers, and I not sure how to describe the sound stage with headphones.
Compared with Audio Sector (also Audio Zone) DAC assembled by Peter Daniels for me and my TADAC.
The more I listen, the more I am impressed with the Gamma1. Listening to acoustic guitar and mandolin, vocals and percussion, the Gamma1 gets the timbre spot on and is nicely detailed. No muffling or congestion with nice natural decay of a picked and strummed strings.
The Audiosector is still probably not burned in and is somewhat more polite and minimally less detailed, but also very nice. The TADAC tones are rounder and lose some detail, but still seem to convey the feeling of a live performance.
I hope to compare with a VALAB as it uses a 1543 too like the Audio Sector. Just my observations using a coaxial input for all three and attempting to volume match, which I always have found to be difficult and can have such a significant effect on perceived quality so YMMV.