When Guru started his Jazzmatazz series back in 1993, it was a genuine nod to the forebearers of hip-hop. The project successfully married his stoic rhymes with the smooth sounds of various jazz greats. But somewhere along the line, the Gang Starr front man veered off his original course. Now, after three progressively different chapters, he returns with Vol. 4, a sonic amalgam of the previous three that produces mixed results. Helming the boards throughout is Solar, the same producer behind Guru’s lackluster 2005 solo effort, Version 7.0: The Street Scriptures. Unfortunately, the beatmaker’s use of ancient drum breaks (“Stand Up”) ...