I'd definitely go for RME as their Firewire implementation is better than anyone else's.
If you don't like the RME preamps you can always connect alternatives to the digital
interfaces. There are possibly other manufacturers with better audio performance but
they're based on Firewire chipsets with a poorer reliability record.
James.
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JRP Music - Audio Mastering and Restoration.
http://www.jrpmusic.net