10-Inch Low-Profile Amplified Subwoofer System - 900 Watt Compact Enclosed Active Underseat Car Audio Subwoofer with Built In Amp, Powered Car Subwoofer w/ Low & High Level Inputs - Pyle PLBX10A - Walmart.com
Pyle Active Down Firing Subwoofer - 10 Inches, Ported Design with High-to-Low Input Level Controller, Invisible Down-Firing Speaker, Color Black, Built-in Convenience - PSUB10A - Walmart.com
Help understanding "High level inputs" - Subwoofers - The Klipsch Audio Community
REL Acoustics Baseline Blue Hi Level Subwoofer Cable | Shop Online - AV Luxury Group
DC Audio Level 4 15" Dual-2-Ohm 1500W RMS / 3000W Peak Car Audio Subwo — Showtime Electronics