My car is arriving in a week or so (hopefully, it's "at the port") and I was able to access the owner's manual in "My garage". I just spent two days copying 575 albums into FLAC.
I see this in the manual now:
USB storage device
Playable formats
MP3, MP4, M4A, M4B, AAC, WMA.
One of the reasons I opted for Harmon Kardon was sound quality. Can anyone reassure me that my system will be able to read FLAC?