[LAU] Motherboard's S/PDIF port

[Ivan K]

If I have a already have a ASUS motherboard with a Coaxial S/PDIF
port, then is there any reason to get the Delta 66 over the Delta 44?
 
  Delta 66: 6-in/6-out, S/PDIF digital I/0 with SCMS control
  Delta 44: 4-in/4-out, no digital port.
 
The only difference between the two cards (besides the number
of in/outs) is the addition of the S/PDIF port on the Delta 66.
 
I know the audio on motherboards is inferior to a good
sound card, but is there any functional difference between
S/PDIF on an ASUS motherboard and an M-Audio card?
 
Thanks.