Guitar Center Inc. said it has completed the acquisition of Music & Arts Center, a privately held retailer in Maryland, for $90 million. The deal also includes the assumption of debt and other obligations. Music & Arts Center, a music retailer with 62 locations in the Northeast, mid-Atlantic and Southern United States, recorded $85 million in sales for the fiscal year ended Jan. 31. Westlake Village-based Guitar Center currently operates 144 stores under the Guitar Center name and 19 American Music locations, which specialize in the sale and rental of band instruments, along with a catalog division, Musician’s Friend Inc.