If you are set on Pioneer I would get the 819 as not only does it have the HDMI connections but it also decodes Dolby True HD and DTS-HD Master Audio, the 519 doesn't. The low end of Onkyo can be a good choice if you do not have alot of sources and do not need analog multi channel outputs or multi channel inputs. A few of the things that I am not crazy about is no Burr Brown DAC's and unless you are buying a Onkyo 876 or 906, the component video is only rated at 50MHz. How ever I find the amplifier sections on the lower end Onkyo to be better than the Sony's, Pioneer, Sherwood and JVC. How ever another thing IMHO to watch out for is that some of the Sony's, Pioneers and Onkyo's rate there lower end recievers amplifier sections at 1KHz only and not from 20Hz to 20KHz. In that price point it is not that you can't find a good receiver, but be willing to accept that there will be limitations and that corners have been cut here and there.
Depending on what your needs are and if you run a very simple system a $500 reciever could work very well for you. But if you want alot of flexability, power & performance and a number of sources, then you might want to seriously look at a higher end receiver.
Plan it out:
*How many sources will you be using?
*How many component video inputs will you need?
*How many HD sources do you currently have & how many might you add in the future?
How big is your room and how loud do you listen to your music and or movies?
*Are you a casual listener or a critical listener?
*Do I want or need lossless audio decoding? If you have Blu-ray I would make sure you have lossless decoding!
Make sure your current speakers can handle the power of the reciever you are buying. Think about future purchases and ask yourself will this receiver do everthing I need it to do today and at least 4-5 years down the road?
