I tried the Fusion 878 card today.   Unfortunately it's not
a simple case of the wrong sample format.

It does actually digitise the line in and the gain control,
mixer input selection, and mic boost work too.  It's just that
there's a huge noise burying the signal, white and Gaussian and
I don't know where that's coming from.

If you install the Fusion 878 and you don't see a Bt878 in
/proc/asound, then try (as root)

 modprobe snd_bt87x load_all

and see if it picks it up then.

Run the card with

 vtcard -d hw:1,1 -r448000 -c1 -b16 -uv @test,i2

and see what you get in @test.   Might be I just have a faulty
card here.

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Paul Nicholson
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