I have to put my vote for the Athenas. You could conceivably get the Teac CR-H220 (in my sig) which has enough power to drive the Athenas to pretty good levels of output. The Teac CR-H220 has three audio inputs/two loops, a subwoofer out, and binding post terminals. The Teac could be had on Ebay for less than $80 and offers the simplicity of having the CD player built in. I am using the Teac in my living room with some BIC towers and a subwoofer and it goes as loud as I care to listen and runs very cool.
In the three months or so that I have had it I have had no problems what so ever, no clipping, no protection activation, no extreme heat issues, no CD read errors. Everthing has worked excellent. The quality of construction is better than pictures indicate and should last your nephew some time.
This isn't to say the Sherwood or Onkyo receivers wouldn't stand the test of time. I just think the Teac is more fitting given the situation (based on your nephew's age and so forth) and not only that, it should be something he can continue to use for quite some time.
