After I made my post above, I drove into town for lunch with a buddy, and we got to talking about audio systems for kids. My friend mentioned that he had recently purchased a Rotel RA-02 integrated amp for use in the recreation room, where the system will mainly be used by his pre-teen and early teen kids. He combined the RA-02 with a pair of Krix Equinox speakers, which are fairly efficient, and he said the system works very well.
This conversation made me do some further thinking about this thread, and I want to amend my comments above. Several points which seem pertinent are:
1. The system needs to address the listening habits of the prospective user, not the seasoned audiophile, so keep your kids needs in mind. Floorstander speakers may not be the best choice, even though I like the idea of something like Vandersteen 1's. A "bookshelf" speaker is likely to be more practical, and easier to drive since it will have less low frequency output.
2. One of the newer models of inexpensive integrated amps might be a good alternative to "classic" separates. It's simpler to use, easier to set up, and if it is combined with efficient speakers it can provide a good taste of good sound. The Rotel RA-02 has gotten very good reviews, it provides 40 wpc, and it is not very expensive. Audio Advisor also sells several other good integrated amps: the Cambridge A500 (65 wpc) for $400, or its smaller brother, the A300 (50 wpc) for $249.
3. An efficient bookshelf speaker (90 db or better) should provide adequate volume, assuming the system will be used in the youngster's bedroom. There are some good choices for lower-cost speakers that should fill the bill:
a. Krix Equinox speakers can be purchased used for $300-350;
b. Wharfedale Diamond 8.1 or 8.2's, which Audio Advisor sells for $200 and $300, respectively;
c. B&W 303's, which have gotten very good reviews, are fairly efficient, and sell for around $300.
Hope all of these posts give you some good food for thought.