actually DZ doesn't use a Layla anymore (I would know since I own his modified Layla now )
his ADAT>ILDA ILDA>ADAT devices are pretty nice, with discrete AK DACs and such
along with a USB>ADAT dongle it's a pretty powerful device...
sound card dacs are ok for most users here and their low cost makes entry to the laser show world very inexpensive which is great... I would not use it in a paid gig but hell I still use mine a lot to mess around (although it's been starting to flake out lately) but even a modified layla is a step up (as are DZ's boxes)