Power cords, most effective placement:

I just bought an aural symphonics power cord. Suggestions on the most effective placement in the system. Transport?, Dac? preamp? amp?
Is your power cord new or used? Even so, it will require some break in. I would suggest that you start with it hooked up to your amp since it draws more current. Leave it there for a good 150 hours or so( if new). Once you hear it come into focus, try it with the remainder of your components and let your ears decide which component it sounds best on. Have some fun with this using some of your favorite recordings that you're most intimate with.
I agree with Sherod about using recordings that you're very familiar with. I find break in with a power cord not to be as long as ICs and cables. 50 hours (high current pull) should get you there. Cord placement?: the source of course....warren :-)
The biggest impact in my system from a power cord upgrade (ps audio statement extreme) was with my digital source(scd-1). I subsequently replaced the stock cords on my cj amp (premier 350) and pre-amp (premier 16lsII) with ps audio exreme statements and heard no discernable audible differences.

As for breaking in the cord, I would suggest one of those IEC to AC adapters, using it on a box fan/heater/lamp-whatever you can use it on that has a steady current draw.

As for positioning, you're prob. going to get the best results with the transport or DAC.

I would try it in ea. position for at least a week and longer if possible. Instead of immediately switching to a new position, put back the PC you were using, as that is what you're most familiar with, as to make a comparison with that piece.

I use a different PC at the CDP, the amp & preamp with good results.
Instructions for audiophile powercord placements:

1. Remove any price tags.
2. Hide receipt onto the safe place from your wife.
3. Mask labelling(if possible) so your wife won't ID it on the internet.
4.(now it's serious) Initially you can place powercord anywhere and after a quite a while of listening reconnect it to a different component etc... etc... etc... until it walks through all of them.
5. Disconnect the treasurable powercord and listen to your equipment with only stock ones before repeating step 4.

Plug into the IEC socket. I find this to be good starting placement.