Using splitter for line input, doesn't work

[jdop2]

Must be something I don't understand here.

I have an Audigy 2 ZS. I just got a secondary source of video, and I wanted to feed two audio inputs into line in, so I used a Y=splitter.

One source (A) works this way, but the other (B) is muted. When I turn off the output of the working source (A), then B starts working.

Is there some reason both won't work at once ?

 

[Nik_I]

i don't think the sound card is capable of dealing with the two sources at the same time. that's about it.