just use one channel for the sub. <fishjam@gmail.com> wrote in message news...have an Alpine CDA-9812RB, with stereo sub pre-out, and AFAIK no provision for switching to mono out. I have a bridgeable mono ... of the HU sub out, or can I sum the grounds of the pre-outs and use ... cables to carry the stereo sub signal? Is this necessary (LF being primarily mono) & does it carry a risk to ...

I have an Alpine CDA-9812RB, with stereo sub pre-out, and AFAIK no provision for switching to mono out. I have a bridgeable mono amp for a ...should I just use one channel of the HU sub out, or can I sum the grounds of the pre-outs and use three of the four speaker cables to carry the stereo sub signal? Is this necessary (LF being primarily mono) & does it carry a risk to the HU?...