I have yet to purchase a DVD player but have done quite a bit of research. I have an HDTV-ready Samsung and Yamaha HTR-5550 receiver. I'm still confused when it comes to Dolby decoders, etc. If the receiver has that feature, does the DVD player need to have it? The RP91 is appealing to me, but I am wondering if the extra $$ is needed or a waste. Please help me understand this.