Well, it's hard to separate the two. The mixer can only get out what the producer put in. If the guitar is compressed right out of the box, or the selection of sounds all have a similar toooone, then the mixer is stuck with it to some degree. I don't think the problem here is necessarily with Andy Wallace, I would look more to the type of live mix JMX had in the studio, the drum mics that were used (what the hell happened with the ride and overhead mics btw?), etc. A good producer is highly attentive to the original tracks having a diversity of frequencies and tones and being mindful of the space they take up. It's really apparent on ADTOE that JP has not been very involved with the drum sounds until now - it shows up in the mix partly because of the way the drums were originally recorded. That's where having a seasoned producer with a diverse background and objective ear comes in. They can suggest mic-ing instruments differently, tracking various parts differently, or simply tossing out ideas the songwriters hadn't thought of to give strength not only to the writing (not needed in this case) but more importantly in the way the instruments sound from the get go.