I am currently in the market for both an amplifier and speakers. I really don't own even a half-way decent speaker to try things out with. I have a pair of Sharp bookshelf speakers. They contain a single 4" driver, weigh about 1 pound, are made of particle board, and are about 10" tall by 6" wide by 4" deep. Their power handling is 5 watts. Sensitivity is unknown.
I have been experimenting with these and the Sonic Impact on AA batteries. I have a test tone CD. When I play frequencies below 60 Hz, with volume around 80db, I get a clicking sound coming from the speakers that is clearly much higher in frequency. I don't know if this clicking is the amplifer clipping or the speaker clipping or something else.
I think this explains a slight raspiness that I am hearing when I play music. Has anybody else used a test tone CD with their sonic impact? What were the results?