3 prong cable vs 2 prong???

Some equipment actually uses the ground. Especially power conditioners. I would be careful, but not overly concerned about using it on any source, or preamp. I would say do not use it on amps, as an amp ground fault would be more able to kill you than other lower amperage equipment with a ground fault. (I have stuck my fingers into 120volt AC power plenty of times, and gotten the major "buzz" from the current. But I would not want to do it with a big power supply amp, nor 240 volt AC.)

gotcha. the cdp that i have only hjas 2 wires anyway, so i dont think it will be an issue. i was gonna try it on my preamp and see what it sounds like till i can finishe the iec mod on cdp. thanks