I’m trying to decide on how much/power of a receiver do I need. I was told I need at least 140w per channel vs the 110w that I liked because of the speakers that I have. I saw a Onkyo 770-Watt 7.2 Channel Home Theater Receiver with 7 HDMI™ Inputs Model No: TXNR708 ($700) that I liked, but it was suggested that I buy Yamaha – 9980W 7.1 Channel A/V Home theater receiver Model RX-A3000BL ($1800). Price is not important, but I’m not trying to spend a lot as well. I NEED/WANT 3D capable, at least 4 HDMI ports, Self calibration, and THX and any other features that’s needed.
Let's start at the end. THX is not a feature. It's a certification companies pay for. IT basically means they paid lucasarts to do some tests on it and it passed those tests. IN reality most receivers IE marantz, denon, yamaha, regardless of THX certification, are very good. In reality, if every piece of equipment in your setup isn't THX-capable, then you don't have a THX certified home theater. This includes the room itself having a low noise floor, and every seat being a good seat by way of room treatments. You need speakers that are both extrenemly loud without distortion, and can be driven by a THX certified receiver (125 w for example is not much power all things considered)
That's not to say THX is bad, it's great. IT helps some people decide. But it also hikes up the price for some products, or cheapens up the component quality on others. Don't be stuck on it.
Now regarding the receiver. Either yamaha or onkyo will be a good choice. IN reality there's few bad choices on the electronics front with most major brands. MY recommendation is to look into warrantied b-stocks/refurbs because the less you spend on something that won't make the biggest difference, the better off you are. Now on that note, the Onkyo allows for stereo subs IIRC. If you've got a pair of matched subs, then the .2 is worthwhile. Otherwise just relax and realize most choices are the correct one. Most companies have quality auto-setup these days, regardless of what it's called.
Finally, regarding watts per channel.
It's a matter of a few things:
1) speaker Power handling
2) Intended listening levels
3) speaker efficiency(and sensitivity)
but do know that the difference between 110 watts and 140 watts is not much. You could probably turn the volume up on both and have difficulty telling at what SPL your amplifier begins to clip. as a general rule of thumb, if you're not doubling up on power, there isn't much to benefit from.
So to answer the original question "how many watts do I need"... I ask you "To which ends?"
