About pre-amps being on or off during break-in: test it. Use an ammeter to see if current is flowing from your cd player to your pre-amp while your pre-amp is 1) on, and 2) off.
My guess is that while off, the input impedance of the pre- is virtually infinite, and while on it is some measurable high value. (Probably not that high though, not on the order of megaohms.)
The circuit theory involved is simple -- while the load impedance is infinite, there is a voltage drop across + and -, but no current flows; when there is an impedance less than infinity, you will still have a voltage drop across the load, and current will flow. (V=IR; I=V/R.)
I never thought about keeping the pre-amp off. Of course, I let cables burn-in naturally by running signal through before, during, and after listening for a while. I believe it is the current flow that may break-in the cable, and not merely presenting a voltage drop across a virtually open circuit (where, as a result of the laws of nature, no current will flow). The current flow requirement in my thinking comes from the (capacitive) dielectric properties of the cable.
Special cd for burn-in? Does it sound any good? There is a market that I missed out on creating. Beaten to the punch! We used to use white noise from a tuner in the high-end shops. Cheaper, and you could meditate to it (at home, not at work, of course). Alternatively, we used to use music. A novel idea since music was what we would ultimately listen to with the system.
