As you can easily see, the CD version on the bottom has been heavily compressed, limited and/or clipped, and sounds massively distorted as a result. In fact, despite the appearance of the waveforms, the CD version still sounds louder, even though it's level has obviously been reduced in the sample I was sent - presumably to match the levels for comparison purposes.
To be completely open and up-front about everything, the files were mp3s - not the best sources - and I haven't yet heard the album myself(*) to confirm the sample is a truly accurate representation, but the samples clips on iTunes are enough for me to be very confident. No mp3 encoder would do this to a file.
(*) Since posting this I've had a chance to make the comparisons, and can confirm that the mp3s accurately represent the released CD in terms of the overall sound, degree of distortion etc. Details here.
I have removed the link in the comments from my last post to the samples which were uploaded (not by me!) to avoid any possible legal issues, but if you are curious to hear the difference for yourself there is a video on YouTube which I link to in this post which demonstrates it pretty clearly.
And of course, this doesn't answer the questions about how, why and where this amazing feat of sonic demolition was achieved - however Ted Jensen says it wasn't him, and I'm inclined to give him the benefit of the doubt - and his colleague, Chris Athens, says on the Gearslutz Mastering Forum thread:
Rick Rubin and Metallica are solely responsible for the end product. They gave the directions, they approved it. They are not rookies and no one at the label can ever bully these guys into anything. Both parties are 800 pound gorillas in the music industry. These guys are smart and in control. You and I may not like their taste, but it's not a Chris Athens record. It's a metallica record and this is what they want to give the record buying public. Only Metallica and Rick know why it sounds like it does.
- which would seem pretty conclusive. Given Ted's original comments, it seems hard to believe that the album was presented to him as it sounds on the Guitar Hero version, so it will be interesting to see if the band or producer Rick Rubin decide to speak out.
Personally, I don't know whether I should laugh or cry. I'm not a big Metallica fan, but to hear this much pure damage done to what was obviously originally a decent recording, in the mistaken belief that it sounds good, is hard to stomach. I'm no audio purist, but the end result on the samples I've heard is genuinely un-listenable.
As I write this, the online petition to have the album re-mixed and re-mastered stands at 2252 votes - I'll be adding one more.
(Edit to add - sadly this album is just one more example of the so-called "Loudness Wars" in the music industry at the moment - I have written a post illustrating why "Louder is Better but Too Loud is worse" and how this affects "Death Magnetic" here.)