[Ark2]

Thought this was cool:

Hesitation Marks was mastered in two different ways - the standard, “loud” mastering (which is what you’ll find on the CD, on iTunes, and everywhere else), and also an alternate “audiophile” mastering, which we’re offering as a free download option for anyone who purchases the album through nin.com. For the majority of people, the standard version will be preferable and differences will be difficult to detect. Audiophiles with high-end equipment and an understanding of the mastering process might prefer the alternate version.

Alan Moulder, who mixed the album, offers a more detailed explanation:

When we were mixing Hesitation Marks we decided to treat the mastering process in a slightly different way to the usual. Since we had tried to treat every other aspect of making this record differently to how we were used to, it seemed to make sense. We were mixing as we went along with the production of each song rather than at the end, so we thought that once we had a song pretty close we would send it off to Tom Baker, our long time serving mastering engineer, to give it some mastering treatment. Normally you wait until the record is finished being recorded and mixed, then take all the mixes to mastering. But we thought doing it again, as we went along, might make us push the process further and spend more time on mastering rather than rush through it at the end. Whilst doing this we became aware of how much low bass information there was on the record. Since that can define how loud of a level the mastering can be, we were faced with a dilemma: do we keep the bass and and have a significantly lower level record, or do we sacrifice the bass for a more competitive level of volume? The biggest issue in mastering these days tends to be how loud can you make your record. It is a fact that when listening back-to-back, loud records will come across more impressively, although in the long run what you sacrifice for that level can be quality and fidelity. So after much discussion we decided to go with two versions. On the main release Tom did exceptional work to maintain the integrity of our mixes and reproduce the low end as much as possible and still get a decent level, although it’s still nowhere as loud as a lot of modern records. The Audiophile Mastered Version is more true to how the mixes sounded to us in the studio when we were working on the songs. Have a listen, turn up the volume and enjoy the experience!