adywan said:
EDIT: just done a short rerecord of the laserdisc 5.1 but this time i recorded it with the soundblaster X-FI crystalizer enabled and this seems to have cured a lot of the problems and also made the whole mix amazingly better. I think i may well go with the laserdisc audio for this project now if all goes well with the whole recording

Woah just a minute, I'm sorry but alarm bells are ringing now.

When you "record" an AC-3 stream off laserdisc surely the stream that you end up with is bit-for-bit identical to the digital data stored on the laserdisc?

The "sound" that comes over the SPDIF is effectively just "noise" (as it's encoded digital data). So how would running it through a proprietary processing system improve it?

Oh and BTW I Googled X-Fi and found this:
http://www.hydrogenaudio.org/forums/index.php?showtopic=54212