What is the Sound of Impedence Mismatch?

I think the second suggestion is a winner. I'm pretty sure I can handle the soldering, but--and I'm embarrassed to ask this--the resistance should be added to the "hot", right, and that is which, the inner plug or outer jacket on an interconnect? And, are resistors directional?

While I'm at it, I am also embarrassed to discover that I have been misspelling impedance all this time.

Drubin, don't feel bad I misspelled the name of the item I have up for auction, twice! Then spelled the word in the manufacturers name correctly in the text. Talk about embarrassing.

Dan yes: the inner conductor. Direction of the resistor is not an issue.
Be aware however that the input sensitivity of the amp will be reduced somewhat, requiring a bit more drive level from the preamp source component.