Should I upgrade power cord for my preamp?

Upgrading the PC to your preamp can make a huge improvement in performance. However, each aftermarket PC is different and it may take several attempts to achieve the timbre that pleases you.

I believe cables should be thought of as a component in the system. My advice is to try a couple from a company like Audio Advisor, who has a 30 day return policy.

It's important for you to use a cable that is rated for low-current components. IOW, you don't need to buy the same cable that your amp is using. IME the heavy gauge cables will have a negative effect on a preamp.

Yes. Lowrider has a great point about AA. You can't go wrong.

Audio Advisor is a nice resource. I have bought from them indirectly via Amazon for same cost plus I get points on my Amazon credit card when I do it that way, which adds some value.

I love their catalog. Reminds me of the old Lafayette or Radio Shack catalogs except targeting good sounding audio, and no low level parts, like resistors and capacitors, though I think you will find a fuse or two maybe. :-)

Based on my limited understanding of how preamps work, it does not seem like it would make a sonic improvement.

One way in which it could make a difference is that the shielding it may provide could reduce noise that may couple into the preamp via the power cord, or (especially if the preamp includes significant digital circuitry) noise that may couple from the preamp via the power cord to other parts of the system. That would include noise components that are at frequencies above the range of audibility, but that may have audible consequences by "intermodulating" with signal frequencies.

So one thing I would look for in an upgraded cord is good shielding. As you appear to realize, particularly heavy gauge is unnecessary (assuming the preamp is not one of those having a monster power supply drawing large amounts of current), and might even be counter-productive per Lowrider's comment.

Also, I would not assume that more expensive = better results. See this thread for further discussion of that, if you are interested.

Finally, a number of members here, including me, have been pleased with modestly priced Signal Cable power cords and cables. They offer excellent value, confidence-inspiring technical characteristics, and 30 day return privileges (less two-way shipping). I would suggest contacting Frank at Signal Cable and asking if he feels that his Magic Power Digital Reference Power Cord would be a suitable match for your preamp, even though it is nominally intended for use with digital components. A reason I suggest that cord in particular is the double shielding it provides.

Regards,
-- Al