I am looking to buy a new receiver for my expanding HT setup. I don't know too much about receivers, so I am hoping to get some advice. I don't want to spend more than about $200 or so. Cheap? Yes, but I'm not the wealthiest member of the forum Here are a couple of options I am considering: Yamaha HTR-5830 Pioneer VSX-515-K Onkyo TX-SR503 Denon AVR-685S A couple of these I would have to buy refurbished, I think. Which of these is the best option? Any other general advice?