OK, this gets interesting. I bought the Sony 50" last year (50XBR800). I've got it hooked to a satellite using a DVI for HD. My 2 DVD players are hooked straight to the TV via component. I never have used the TV speakers - don't even know if they work. I started out hooked up through a receiver. I am not using any video upconversion through the 3803. I'll give you whatever help I can, after all, I AM a 2 week veteran with the 3803.
If you are hooked up for audio with analog, was that the 5 cable piece to do DVD-A or are you just using the simple left & right composite cables? I would suggest that you look at either coax or optical connections for your audio stuff. Not much difference between the 2 and DO NOT spend alot of money on the cables (please- no flame war here).
I don't know much about wiring an amp into the mix, so I can't help you there.
I'd urge you to take a look at Blue Jeans Cable (online) for your interconnects. Excellent materials and quuality without breaking the bank. Make sure you get them long enough to allow you to work with your components. Oh yeah, speaker wire = 14ga at Home Depot. Measure what you need in tiotal and have them cut you one big honkin' piece from the bulk roll.
