I remember listening to Confield realaudio previews back on the old Warp site and somehow getting the impression that it was a noise album. Not sure if that was a shock though.
Gantz Graf was quite a huge step forward from Draft, but I was more surprised than shocked. I remember that one also sounding like noise, but I was a more seasoned Ae listener by that point.
As Stickfigger says, known(1) was pretty confronting at first, but I fkn love it.
Osla for n was a bit of a shock, as I didn't think they could get any more next-level in their rhythms.