digital input sampling rate on mac pro

[docdan50]

I have a behringer ultramatch pro I use as an analogue to digital converter to record vinyl. It can be set to 24/96. I feed that over spdf toslink to the optical input on my mac. In audio midi the sample rate choices include 48k and 96k. When I try to set 96 audio midi will not hold it there and goes to 48. When I set the a/d converter to 48 audio midi holds 48 just fine. I output 24/96 from the mac to a dac magic. The digital recordings sound fine, I just wonder why I cant set the mac on 24/96. If I use the analogue input on the mac pro and do a/d conversion inside the computer I can set 24/96. Any explanations?

 

[The Computer Audiophile]

Hmm. I wonder what the Max sample rate of the optical input is? Also, I wonder if the A to D is really outputting 24/96?

 

[docdan50]

I will feed the output of the behringer to the dac magic and see it it shows receiving a 24/96 signal when I get a chance. I have looked for specs on the mac optical input but havent found any info.