Bruce Hofer (founder of Audio Precision) did a recent AES Convention lecture on many topics pertaining to low-THD circuit design, including parts quality in both capacitors and resistors. He was kind enough make the PowerPoint slides available for download in his May newsletter, which can be found here: http://www.ap.com/kb/list/2
You do have to register to have access, but there's a wealth of tips available from one of the true modern masters of analog audio design.
You do have to register to have access, but there's a wealth of tips available from one of the true modern masters of analog audio design.