According to the BDP-1 page on the Bryston website, it "can play all high resolution FLAC, WAVE and AIFF files up to and including native 192/24 bit files as well as Apple Lossless (m4a), WMP and MP3".
iTunes does not natively support FLAC, so you would need to use a third party conversion program to convert FLAC files to ALAC or AIFF.
Steve