I can't speak specifically to CI dacs, as I've not used them, but I do have some experience with the SB as a transport.
I've used the $24 12' toslink from uniqueproductsonline.
http://uniqueproductsonline.com/gltodiopca.htmlI prefer it to any coax spdif until you get to (for me) that stratospheric cost of the $200 Stereovox xv2, which I now use. That being said, my toslink is a 280 glass strand implementation. The more expensive glass toslink from PartsExpress is a 68 strand version is supposedly equivalent to the SoundProfessionals toslink which others have found preferable.
http://www.partsexpress.comsearch on 'glass toslink'
Personally, If I had an unmodified SB2/3 (without a spdif transformer, and the chip inductors removed that are there for FCC compliance, not quality of digital transfer) and a transport with good coax spdif output, I'd use a good coax to connect to the VDA 2 and use the toslink to connect to the Squeezebox.
FWIW,
Paul