On January 23, 92Y School of Music will host “Countertenor-Palooza,” an online discussion featuring some of opera’s leading countertenors. Host Naomi Lewin will be joined by countertenors John Holiday, Aryeh Nussbaum Cohen, and Samuel Marino. Making his debut with the Metropolitan Opera next fall in Matthew Aucoin’s “Eurydice,” Holiday recently received national acclaim as a finalist on this year’s season {…}