Yeah, but what's actually clipping -- the recording itself, or the input stage of your preamplifier? That's the real question you must answer. Most preamps can handle 4.5volts without clipping, but a few may not handle it gracefully...
What is the CD player plugged into and what is its input overload rating? You might need to consult the manufacturer of the preamp (or amp) on that point. Manufacturers don't always include that specification.
What Sogood said, two volts.
Does your CD player have volume control? They can put out up to 5 volts at maximum, and most preamps will not like that. If so, turn the volume down until the distortion stops. Like PLato said, the manufacturer or distributor can tell you where the normal volume setting (dB) has to be set for the equivalent of two volts.