It's not that there's buzz in the speakers when the unit is on, there is buzz in the speakers even when the speakers are disconnected! When this happened before I was actually carrying one speaker around the house trying to figure out what was causing it. I think it was the electromagnetic radiation (or whatever) produced from the CFLs when the dimmer switch downstairs was not at maximum. (I didn't put the CFLs in the lamp, and now they're incandescent.)
Now I'm not sure what's causing it. I replaced the dimmer switch and still no change. When the speakers are connected and the unit is on there is more hum/buzz (not more than previously), but I'm wondering if the hum/buzz produced by the CA-1000 is made worse by whatever is causing the speakers to buzz when they're going "solo".