As the Allman Brothers multi-night stand the Beacon Theater works towards its midway point, guests are arriving fast and furious. Last night, the Asbury Juke Horns emerged near the end of the Allman Brothers Band’s first set, accenting ‘Into the Mystic,’ ‘The Night They Drove Ol’ Dixie Down’ and ‘The Same Thing.’ A bit later, the Allmans returned for their second set alongside a pair of blues legends: Elvin Bishop and the 92-year old Pinetop Perkins, who cut his chops playing piano in Muddy Waters’ band. After running through renditions of ‘What the Hell is Going On?,’ ’19 Years Old’ and ‘Moe Joe,’ Bishop and Perkins stepped offstage, while the Brothers dipped into ‘Egypt.’ For those keeping score at home, Hubert Sumlin, Susan Tedeschi, Devon Allman, Gary Rossington, Peter Frampton, Jay Collins, Will Calhoun and Roy Haynes are among the artists who have joined the Allmans at the Beacon this March. After a night off, The Allman Brothers Band will return to the Beacon tomorrow.