By Don Heckman Los Angeles – April 26. (Mon.)  Karen Marguth Quintet.  Featuring Eva Scow, mandolin.  Singer Marguth and mandolinist Scow have been producing some fascinating displays of briskly swinging voice and mandolin jazz.  Hear them in the always friendly, laid-back setting of Charlie O’s.   Charlie O’s.    (919) 994-3058. – April 28. (Wed.)  Kevin Eubanks… Read More Picks of the Week: April 26 – May 2