Anything from Aja on
Some pre-Aja
IMHO, "Aja" is the best they ever did, and in fact, I consider it to be the "best" album ever made (and many audio engineers agree). I'm not really talking about it just from the musical side... Excellent writing, spectacular musicians, etc. But the actual recording and mixing is really something else. It really is amazing when analyzed technically, and a lot of audio schools use it as an example of what to do.
Mark