[DD1 testing HU through amp - no signal/40hz but distortion turns on]

Tried to find my specific issue via forums and google but no dice.

If I test my headunit (Pioneer 80PRS) for distortion via rcas everything works as expected and I end up with vol 57/60 showing clean.

 

I tried testing via the alternate method, through the amp and I can't get a signal or 40hz light but the distortion light does come on at vol 53/60. I've reread the manual and triple checked all settings, xover, filter etc. I cannot get a signal or 40hz light with the gain of the amp all the way down as the manual suggests. As soon as I turn the gain up at all the signal and 40hz turn on.

 

Should I just go with the headunit only method and ignore the results I'm getting through the amp? Any idea why it doesn't work through the amp as the manual recommends?

 

Thanks

[What version of SA 15 do I have?]

I bought this sub years ago and forgot about it. Came across it in storage and thought it'd be fun to hook it up. Going to build a custom box for it just need the specs. Google was not helpful. Appreciate any insight you all can give me.

 

I can take more pics if needed.