Aes Interface For Recording Masters Options

[EHartman]

So here at my work they have decided that the masterlink needs to go and they want to be able to print mixes to another computer and have that accesible on our network. Right now we go Stereo Bus 9080J-> PSX100-> Masterlink.
There is an IMAC laying around and what I am looking for is a basic Firewire interface with At least 1 AES Inout and 1 AES output. I Don't need an A/D or D/A just AES IN/OUT. Of course Core Audio Compatibility as well. It seems most interfaces on the market have the converters and preamps and all that kind of stuff as well But I am just looking for bare bones AES In/Out.
Second questions is if the audio has already been converted externally what kind of quality issues are really needed besides reliabilty in the interface. I would think all it is doing is transfering a digital signal into the computer. Any help would greatly be appreciated

Eric