Bi-amp NAD M15/M25

Hi... running a 5.1 system and the NAD M25 allows up to a 7.1 configuration. Is it possible to bi-amp my 2 main L/R speakers with the 2 unused output channels on the M25, like I did with my previous NAD T785 surround sound receiver? There is no mention in either the M15 or M25 user's manual. Many thanks!