Our customer supplied this older amp and subwoofer to install on his 10th generation Honda Accord Sport. The factory Honda premium sound system had a "sub" mounted in the center of the rear deck. These factory Honda subwoofers are typically only rated at about 50 Watts and when cranked up can rattle some of the plastics on the rear deck and C-pillar area.
Those used to fuller sounding bass offered from a 10" or 12" subwoofer will be sorely disappointed with these factory systems as the bass offered is barely noticeable. Radio replacement is unlikely with a newer car like this as so much is integrated into the factory screen and Apple CarPlay/Android Auto are standard. When doing a amp and subwoofer install, it's important to also unplug the noise cancelling system which is located behind the glovebox above the cabin air filter. Otherwise, the speakers will emit weird sounds to try and combat the bass generated by the aftermarket amp and sub.
For the signal to feed the amp, we connected a 2CH line out converter to the rear deck speakers and not the subwoofer. We find the factory subwoofer signal tends to be filtered heavily by the stock amp and the output does not sound great. Instead you can get a fuller frequency signal from the rear 6.5" speakers and filter as needed through the low pass on the amplifier. The amplifier our customer had supplied is an older unit and was on the larger side and could not fit under the seat or under the trunk floor. We wired it in such a way that the sub enclosure could be removed easily if he needed to move larger or longer items.
Generally speaking, the rear seat back is rarely folded down as a child seat is in place for our customer's daughter. We also noted that turning off the SVC Neural setting on the Honda head unit made for much better sounding bass from the aftermarket subwoofer setup. Aftermarket subs are not an issue with new cars and there's many ways to go about. If you have any questions about putting a subwoofer in your vehicle, feel free to contact us today.