SPDIF Encoding Over TOSLINK or Optical Connection

[FunTimes]

Basically, I just wondering whether or not SPDIF Encoding on an external sound card and sent across an Optical Cord to my reciever will corrupt or have any negative effects on the subs?

And as an additional source of confirmation one way or another, an optical connection is capable of supporting two discrete audio channels without mixing, correct?

Thank you.