Helix DSP Pro MK2, RCA Low level sensitivity for Headunits over 4 volts.

I've read the DSPPRO2.PDF, it explains in good detail how to adjust the input sensitivity for High Level inputs clearly. But it’s very vague on low level (RCA) input sensitivity for HU units that have more than 4 volts of output. Really nothing in the manual for over 4 volt HU input.

I opened my Helix DSP PRO MK2, and played a 50Hz Sine Wave (0db) at 75% percent volume on the SUB channel. The Clipping light came on, and I could not adjust the potentiometers up, as they are fully clockwise from factory, which leaves no room to adjust.

Same thing with my Mid-Base. I played a 200Hz Sine Wave (0db) at 75%, was getting a clipping light. The clipping light will stop at 72%percent volume, but anything about 72% it clips, and i can't adjust because the potentiometers are fully clockwise with factory default setting.

Is there any way to adjust the RCA Low level sensitivity for over 4 volts Headunits? My Headunit is pushing 5.2 volts. It the Kenwood Excelon top of the line DNX997XR

Ever thought about using the high-level input for your line-level outs of the headunit?
The high-level inputs can be set from 5V to 10V on the DSPPro. Just read their manual about setting this up.

1. You have to find the max undistorted(the volume where your Headunit starts to get into clipping) Volume of your Headunit.
This works best with an Oscilloscope (look for a Hantek 2000 Series one i.e Hantek 2c42 Handheld Oscilloscope. costs around 90 dollars)

2. when you found the max „clean“ volume of your headunit set it to this volume and then go to your DSP and rotate the gain screw until clipping light lights up.

everything but using a oscilloscope is nothing more than guesswork in my opinion.

FYI your DSP is not able to get adjusted for over 4 volts because most aftermarket headunits doesnt have more than 4 volts output sensitivity

I use the volume offset on my Kenwood headunit to tone it down so that it will not overload my JBL MS8 2.8v inputs. My Kenwood is also rated at 5v output too.

I don't have to worry about anyone else clipping my equipment and I can still add more for quiet tracks.

Normally I am using -4 volume offset for my CD and USB drive. -5 volume offset for the radio, iPod & etc.