2019 JBL Question on signal

Can the sound signal be caught at the JBL amp Black plug (J141) on pins 2,3,4 & 5 before going in to Amp and ran to a DSP or do you need to catch the signal on the output of Amp as the way everyone is doing at moment.

The pins reference:
141-2 (L-) - B - W-B Sound signal (Left) Audio system playing
J141-3 (L+) - G - W-B Sound signal (Left) Audio system playing
J141-4 (R-) - R - W-B Sound signal (Right) Audio system playing
J141-5 (R+) - W - W-B Sound signal (Right) Audio system playing