Looking wonderful Vladd, loving the details and the essence, but to my mind the composition is currently compressing the work’s potential.
The horizontal from his head in line with the owls is dividing the picture plane in equal intervals. Making these horizontal divisions unequal will relax the composition.
Currently the evenly spaced vertical forms of the background are creating tangents with the figure whilst tonally competing with the figure.
Presently the composition favors the exquisite details you have labored over with such skill in preference to the emotional narrative. Orpheus mythologized for music of such exquisite elevatory , transcendent and transformative beauty is being shown from a down view and hence foreshortened, contained/ visually weighted within a circle rather than transporting the viewers gaze in sympathetic ascendance with his music.
With regards muscularity - the muscles are popping as if engaged in physical strain, not the ease charm and almost feminine grace associated with Orpheus or found in such modern contemporaries such as Jimi Hendrix - slim, graceful yet powerful.
In adherence to design über alles what I have suggested, I do so as a friend and fellow artist not as detractor of your work and labors which I admire.
Boozy