Originally Posted by gr8f8
1) Do nothing...won't be able to tell until you're in a dedicated environment.
You're basically correct.. room treatments will probably enhance your listening experience more than anything.
2) BiWire by running speaker line from one set of posts to the other. (I was told this was just as effective as running a line from the receiver.)
Biwiring will gain you the following: redundancy in case one of the wires gets cut, and a total higher gauge (2 x 16 AWG instead of perhaps 1). You're not going to hear a difference no matter whether you're in a dedicated room or not.
3) BiAmp by using 5250 as main wired to bottom end and another 5.1 Yamaha 70W (already own) to high end.
This is only going to help if you've already got a very nice separate power amp and want to step it up even further. At that point, your limiting factor is the speakers themselves anyway.
4) Buy either Panny or JVC digital receiver. I like the JVC 402 because it has HDMI. Any quality difference? Wait for NuForce?
Given you current receiver is a 5250, the first thing I would do if I were you is upgrade to a 7.1 receiver (with preouts) or pre/pro. It's already digital, so the receiver's not that bad, but I'd rather start off with a $700-1000 pre/pro and wait on the amp than get a $2000 amp and use it off of the 5250.
5) Use the 5250 as pre and buy decent power amp. How many watts?
Remember that quality is as (or more) important than a wattage rating. Nevertheless, somewhere around 150-200W is a good place to start researching for the 60s.
6) This one's a little out there....keep 5250 as pre and buy 5 stereo amps to vertically biamp each speaker. Would a pro amp like a Crown XLS 202 work in a home environment?
Overkill while still using the 5250. Look at other upgrades before this. Yes, you can use a Crown XLS 202, but they're quite loud so you'd want to have them in a separate room. I'd just as soon buy a 5 or 7 channel amp instead of five 202s.