The cables are plug in this way.

Cable 0 connected to Preamp A, Positive output. (n+n side, toward the sample)

Cable 1 connected to Preamp A, Negative output. (p+n side, backward the sample)

Cable 2 connected to Preamp B, Positive output. (n+n side, toward the sample)

Cable 3 connected to Preamp B, Negative output. (p+n side, backward the sample)

Then, each cable goes to the jonction box:

Cable 0 goes to label unused. This goes to cable 5 and 6. The output from the RAL amplifier is cable 15 A/B

Cable 1 goes to label 6. This goes to cable 9 and 10. The output from the RAL amplifier is cable 14 A/B

Cable 2 goes to label 5. This goes to cable 4 and 8. The output from the RAL amplifier is cable 13 A/B

Cable 3 goes to label 4. This goes to cable 1 and 3. The output from the RAL amplifier is cable 12 A/B

From the RAL amplifier.

Cable 12 goes to Silena 9418 #1 0-15 channels.

Cable 13 goes to Silena 9418 #1 16-31 channels.

Cable 14 goes to Silena 9418 #2 0-15 channels.

Cable 15 goes to Silena 9418 #2 16-31 channels.

Therefore,

the Preamp B is plotted in Silena 9418 #1, n+n side channels 16-31 and p+n side channels 0-15.

the Preamp A is plotted in Silena 9418 #2, n+n side channels 16-31 and p+n side channels 0-15.