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Technics SU-C800U/ A900S how to connect to SH-GE90??

Hi, i am having difficulty connecting my Technics su-c800u pre amp and my a900s power amp to a Sh-ge90 DSP
I have wired pre out from the pre amp to the input on the DSP and the output of the DSP to the input on the power amplifier, the equalisation works and sound passes through but the analyser display shows no signal??? Where am i going wrong??