I bought my 661 for the lossless audio. In my experience, it's kind of hit and miss. Some PCM tracks are a noticeable difference, some aren't. It can be pretty dramatic, as with Blackhawk Down. But with some movies, (Casino Royale, Underworld Evolution), I didn't really notice a difference between PCM and DD. If your receiver is only 4 months old, I don't know if it's really worth it.