My experience was that Toslink creates much more jitter, very noticeable when compared to other types of digital connection in the same transport and DAC combination, resulting in significant degradation of sound, exactly along the lines of what James stated.
This is true for any transport and DAC I tried, including some 10K+ combinations.
What is to be accomplished by using BCD-1 as transport only, unless you have some extremely good DAC you love?
Why not get just a transport in this case, Bryston one will be coming out I believe?
In regard to BCD-1 on its own and the sound quality, be ready to dish out considerably more to get better performance.