Maybe this is a dumb newbie question, but can one run 6.1 on a 7.1 receiver? I'm thinking specifically about the Yamaha 657, if that makes a difference. I'm thinking about getting the Yammy and also thinking I may want a set of matched speakers (I currently have Cambridge Model 6 fronts and Yammy NS-AC3 and NS-A770 center and surrounds, respectively) and many speaker sets now are 6.1. I know I need a sub. I guess another possibility would be to pick up a pair of Yammy NS speakers, and a sub, though I don't know if current NS speakers would be matched with my 8 year-old ones. Thanks for your input. Also, any recommendations for sub $500 HT speaker sets would be welcome. I don't think SWMBO will let me go above $900-1000 on HT equip @ one time
reschaff- you should be fine running 6.1 channels on the 657. I have the 657 and I'm very happy with it. Try not and pay the regular $499 price for it. You should be able to get it for about $420 or so. There's even some authorized online dealers that have it for about $400. Saw a few this week, but forgot exactly what sites (I know, not much of a help there).
Not many sub $500 speaker set-ups that many would be happy with. Even $1K is tight with a decent sub. Good subs are usually around $400 at the cheapest. Then a few hundred for fronts and that only leaves you with a little cash for the rest. It's best to build slowly but surely. I (and I've seen others write this, too) recommend going the route of buying 2 front speakers and a matching center right off the bat (those are the ones that need to match for sure). Then save some more cash, or spread it out a bit and it doesn't look like as big of a purchase to your wife. I feel the same way sometimes- it's weird I feel bad spending $1500 at one time, but if it's 3 different purchases of $500, it seems better to me. Anyway, buying the fronts and the center first allows you to get better quality equipment (if that's what you want). Then you can finish up the rest of your HT in the future. Some people even buy more inexpensive fronts and eventually move them to the surrounds.
You have a great start by looking at the Yamaha receiver.