Power Cord Priority

try it on each. overall the digital source may be more sensitive, but preamps (esp tubed) are also very sensitive...

CD/SACD player first.

Recently I read that Nordost's opinion is to put the best power cord at the beginning, ie., from the wall to the power conditioner. I always used to start from the source first. Though often used to defend the idea of source as most important, it's funny how "garbage in = garbage out" can run both ways. Personally I am taking this advice and working from the wall out and so far I'm not disappointed. Spreads the benefit to everything. Your inevitable second cord going to the amp then the source.
Try it in all places and pick your favorite. Then try again in a couple weeks.

I appreciate each response. Conclusion appears to be to try the cd/sacd player first, then the preamp. Can't implement the wall to power conditioner since I am using an internally hard-wired surge-protecter/conditioner. Aagin, thanks for taking the time to pass your experience on to me.

If you don't plug into a conditioner, go first with your weakest power supply. That's usually your digital gear.