I have a quick straightforward question that I'm hoping someone can help me with. I am looking at an Alpine CDA-9831. It was a HPF/LPF available from the menu. I want to use the HPF to filter the bass from my main speakers, but does the HPF also cut the low frequencies from the subwoofer pre-out?
Yes it does! Either use the Xover on your amp(s) to set your cutoff frequencies or set BOTH of the HPF/LPF setting in the 9831 to 80Hz and you will be fine. I have the same unit and I have my HPF/LPF turned off and use the amp (which sounds better to me as I've done it both ways).