Up for sale are 2 very good condition Martin Logan Depth Subwoofers.  They comes with the original box, manual, ETC spikes etc.  They were never over driven, owned by an adult

Depth's innovative three-woofer BalancedForce™ design nullifies cabinet vibrations that produce loose, fuzzy bass—common to traditional subwoofers. Its proprietary switching amplifier supplies explosive power, outstanding efficiency and precision at all sound levels. Depth's advanced servo control system continuously analyzes driver performance and corrects any deviation from the original signal—resulting in pure, powerful bass throughout your listening room or home theater. Low-mass driver design, precision low-pass filters and flexible control circuitry enable flawless integration and optimal blending with any existing speaker system—from Martin Logan electrostatic to conventional dynamic loudspeakers.

Specifications

Frequency Response: 20–150 Hz ฑ3 dB Anechoic through LFE effects input. Input Impedance: 20,000 ohms Low Pass Filter Frequencies: 30, 35, 45, 55, 65, 80Hz High Pass Filter Frequencies: 40, 70Hz Phase: 0ฐ, 90ฐ, 180ฐ, 270ฐ 25Hz Level Control: ฑ12 dB Woofer Type: 3 x 8" (20.3cm) high excursion, woofers in a BalancedForce™ array Amplifier: 300 watts rms (500 watts peak) Inputs: RCA Line Level Left & Right; RCA LFE; Speaker Level Outputs: RCA Line Level Left & Right; RCA for Multiple Subwoofer Connection Weight: 65 lbs (29.5kg) Dimensions: 16.25" H x 16.6" W x 16.15" D (41.3 x 42.2 x 41cm)