Thanks for your reply.
For Sad but true, I wonder if some Marshall amps were used ? Have you ever tried to use the IIC+ block and a marshall block to tonematch Sad but true ?
One more thing Guitarjon : On the Black album (and maybe on other albums), James played one guitar track for the left, one for the right and a "thickener" as he said for both (center). This thickener isn't played all the time for layering and we can hear when it's present or not. When you tonematch for example the left guitar, do you take a piece of audio guitar only with this thickener or without ? I think it makes a difference.