Doug, you walked right into one of my most common topics, which is Gain vs. Power. They're often confused. If you're going to mix powered studio speakers with a home system, you'll have to deal with some incompatibilities, such as you've already found.
Simply put, gain (voltage) influences...
The question, is how much power do you need? That's also a complex one, since it gets into what your speakers are, how efficient they are, if you want maximum dynamics, and so on. It's not like you are usually going to notice when you run out of power.
I'll come back when I have more time, but how manufacturers fool you is by giving output ratings for one or two channels, or as Clinton stated, giving a worthless output rating for one channel. Receivers generally are capable of pretty decent power output per channel, but don't have enough...