I was looking into AC-3 RF decoders for LD, and I found on ebay that alot of people mention DD decoders, THX decoders, DTS decoders, DD Pro Logic II, recievers, preamps, etc.... And now a days on Best Buy you see recievers bundled with decoders. Is there any lose in quality or is it just a sign of technology evovling?

Also is there any difference between Pro Logic and Pro Logic II? I have a low cost reciever that decodes DD and DTS for under $100. It says it has Pro Logic decoding, but it being a low cost it really only has the Dolby Digital logo and some proprietary surround sound logos. I wanted to know what where its decoding capacities.