Yeah, I am not familiar enough with either chip, but they are both audio amp chips. Sometimes one manufacturer makes the same as another and puts their prefix on the existing number. Was hoping that might be another source.
You could probably do the same thing on the NEC website. Just find their contact link and ask them for the data sheet. I have had very good results from several manufacturer's websites in this regard, Sometimes it takes them a few days but you usually get an e-mail with a pdf file attached.
MP