Bubba, what kind of fidelity could she expect with those Sonic Impacts?
Using them on FedEx Express Large boxes they were extremely clear. I was quite surprised at the clarity (who wouldn't be when they were listening to a speaker made of a cardboard shipping box).
They weren't very harsh. They're just damn good sounding speakers. Especially for the price.
They are lacking a little in the low end. Running them with my subs I got very, very tempted to replace my speakers with them they were that good. But I couldn't get them to blend with my subs as well as I can get my speakers to blend with my subs. 'course my speakers were designed to be used with my subs, so they blend very well.
I had a friend over and played a Sarah Mclachlan track off of a CD for her (w/out telling her that she was listening to FedEx boxes). Turns out it was one of her favorite songs. She said she'd never heard that song played back so cleanly. It was so clean that she'd heard a bunch of stuff that time that she'd never heard before.
Was funny because she couldn't figure out where the sound was coming from when I asked her. After she gave up I told her she was listening to the FedEx boxes sitting on the floor.

She still didn't believe it. So I made her hold onto one of the boxes while I played it again. The look on her face when it finally dawned on her that in fact it was a cardboard shipping box that she'd been listening to...
For only $20, they're worth a try.
http://www.target.com/gp/detail.html/sr=2-3/qid=1124736935/ref=sr_2_3/601-2854713-2902558?%5Fencoding=UTF8&asin=B0001HKVKQEd of The Horn Shoppe sent me a pair and told me some good ways to get them to sound better. It involves peeling the cardboard disc completely off the soundpad (but leaving the little foam pads the cardboard was adhered to) and directly epoxying the soundpad to the surface you're going to stick it to.
He also figured that a 2' x 3' piece of foam core board or equivalent material would be the best size/shape/material for the soundpads. In my testing I did find the larger FedEx boxes to sound a lot better than the smaller ones. I'd imagine that a 2' x 3' piece of foam core or Gatorboard might take care of a good deal of the low end problem.