John, have a look at this site http://grailtone.com/ Liam's right though, if it all sounds good in the live mix, then 9/10 pished-oot-their-heid punters won't tell the difference. I guess there are some signature tones like The Edge's one-trick-pony sound that you do have to work on, but for me, I'm not trying to re-record the original and want to put my own ham-fisted stamp on a song.