A4: Audi hidden amp install with a JL Audio 8″ subwoofer Leave a Comment / Audio, Custom Fabrication / By Ultra Auto Sound A4 is a super nice clean car…..thats why it needs a super clean install. New focal FPX4.400sq amplifier Amp and speaker crossovers hidden but can still be adjusted through the compartment opening. A nice place for a subwoofer Share This:FacebookTwitterEmailLike this:Like Loading... Related