24-year-old Venezuelan electronica artist-producer Arca, aka, Alejandro Ghersi, did his highest-profile work on Kanye West’s Yeezus, but solidified his dominance with the mastery of sound heard on his &&&&& mixtape. Xen is his second “official” full-length work. Working without the limitations that starring vocalists bring (though conversant in using the human voice as an instrument), Arca succeeds largely because he allows few defining centers of gravity, preferring a free-flowing non-linear sense of motion that’s comfortable leaving great amounts of space between its shifting notes. “Fish,” for example, lingers without support, crafting a fragile sense of crystalline beauty.