Prefuse 73 — the production alias of Guillermo Scott Herren — pushes the outer boundaries of hip-hop into the terrain occupied by Aphex Twin and Autechre. Slippery snippets of micro-edited samples dance elegantly for a few measures, then stop and chatter away in alien tongues. Elsewhere, jittery beats unkink and smooth out into sweet, funky breaks, then reverse course or just melt away. Even voices are frequently chopped, sequenced and rendered secondary to the groove in these productions. As a whole, the body of work produced under the Prefuse 73 moniker is consistently challenging and usually rewarding. If it suffers, it suffers from fans' preconceptions that an artist should be strictly hip-hop or strictly electronic, but Herren refuses to compromise his vision. Expectations be damned, he sequences the beat of his own drummer.